JP2002175731A - Airtight electric wire and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive airtight electric wire and its manufacturing method with easy terminal working and superior productivity capable of positively preventing leakage from an electric wire terminal part and infiltration of oil, water, or the like into an electric wire interior by a capillary phenomenon. SOLUTION: This airtight electric wire comprises a stranded wire conductor formed with an airtight part at least in one part in the longitudinal direction and an insulator covered on an outer circumference of the stranded wire conductor. It is characterized by that the stranded wire conductor has a plurality of conductive element wires and a filler comprising thermosetting polymer as a mandatory, composition, the conductive element wires are arranged in an outermost layer, and space between each conductive element wire is penetrated by hardened objects of the filler at the airtight part of the stranded wire conductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can reliably prevent oil or water from entering the inside of a conductor due to a capillary phenomenon or leaking from a wire terminal, and can easily process a terminal to improve productivity. Also relates to an excellent hermetic wire.

[0002]

2. Description of the Related Art In electric wires used as lead wires of various devices, a stranded conductor obtained by twisting a plurality of conductor strands is used as a conductor for the purpose of improving the flexibility. Usually, this kind of electric wire is subjected to an appropriate terminal processing according to various uses after removing an insulator at a terminal portion and exposing a stranded wire conductor, and is provided for actual use.
At that time, if oil, water, or the like is present near the end of the electric wire, they propagate inside the conductor by capillary action and penetrate in the longitudinal direction of the electric wire, causing various problems. Such a phenomenon occurs, for example, when used in an environment where there is a pressure difference between both ends of an electric wire, such as a lead wire used in an oil case of an automatic transmission of an automobile. Especially remarkable.

[0003] Conventionally, as means for preventing oil or water from entering the inside of the electric wire and leaking oil or water from the end of the electric wire, for example, Japanese Patent Publication No. 1-59476 discloses the means. A method of arranging a wire having a conductor exposed portion inside a wire holding case for fixing the wire to an oil case, and filling a thermosetting resin such as an epoxy resin between the exposed conductor strands of the wire. And Patent Publication No. 28251
As disclosed in JP-A-43-43, a terminal holding plate formed by sealing between a terminal insertion hole of a base on which a plurality of terminals are mounted and the terminal by soldering is formed integrally with a cylindrical housing. A method using a connector in which a sealing member for preventing liquid leakage is attached to an electric wire introduction portion of the cylindrical housing, or a stranded wire as an electric wire as disclosed in JP-A-2000-243151. There has been proposed a method in which a thermoplastic resin fiber bundle is arranged in a gap between conductor wires constituting a conductor, and the fiber bundle is heated and melted to use an electric wire that forms an airtight portion.

[0004]

However, first of all,
In the case of the method disclosed in Japanese Patent Publication No. 1-59476, since a thermosetting resin such as an epoxy resin used as a filler does not follow thermal expansion or thermal shrinkage and easily cracks. Depending on the case, there was a fear that an oil leak would occur. For this problem, for example,
Japanese Patent No. 2766558 proposes an oil leakage prevention wire holding case that can use a resin material having good followability and hardly causing cracks. Such a wire holding case is disclosed in the above-mentioned patent. Gazette No. 2825143
As in the case of the connector disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, there is a problem that the cost is increased because the shape is very complicated and special.

[0005] Next, as disclosed in Japanese Patent Application Laid-Open No. 2000-243151, a thermoplastic resin fiber bundle is disposed in a gap between conductor wires, and the fiber bundle is heated and melted to form an airtight portion. In the case of such a method, a step for forming an airtight portion is necessary, and the productivity is reduced as compared with a general electric wire, and a thermoplastic resin fiber bundle is used as a filler, so that the electric wire Depending on the use environment, it is necessary to use a thermoplastic resin fiber bundle having a high melting point, such as a fluororesin, and there has been a problem that the cost increases.

The present invention has been made based on such a point, and an object of the present invention is to prevent oil or water from entering the inside of a wire or leaking from a wire terminal portion due to a capillary phenomenon. It is an object of the present invention to provide an inexpensive hermetic electric wire which can be reliably prevented, is easily processed at an end, and is excellent in productivity, and a method for manufacturing the same.

[0007]

Means for Solving the Problems To achieve the above object, an airtight electric wire according to the present invention comprises a stranded conductor having an airtight portion formed in at least a part of its length, and an insulator coated on the outer periphery thereof. An airtight electric wire consisting of:
A plurality of conductor strands and a filler composed of a thermosetting polymer are essential components, and a conductor strand is disposed on the outermost layer, and in the hermetic portion of the stranded conductor, curing of the filler is performed. An object is invaded between the conductor strands.

At this time, it is desirable that the conductor strands disposed on the outermost layer of the stranded conductor are radially compressed so as to be in close contact with each other.

Further, it is desirable that the filler contains an expansion component.

[0010] Further, the method for producing an airtight electric wire according to the present invention comprises:
When twisting the stranded conductors, the filler is plastically deformable, and when the filler is hardened,
The method is performed under the condition that the expansion component in the filler acts on the stranded conductor covered with the insulator.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The constituent material of the conductor strand is not particularly limited, and the usage conditions (application,
In consideration of required functions, etc., any of conventionally known conductor materials can be used.

The filler composed of a thermosetting polymer used in the present invention is a thermosetting polymer formed into a linear shape. The reason for using a thermosetting polymer is to prevent the polymer from being dissolved by oil, chemicals, and heat, and to allow the thermosetting polymer to penetrate between the conductor strands by the adhesive action when the polymer is cured. It is. Here, the state in which the cured product of the filler has penetrated between the conductor strands, when there is a gap between the conductor strands, refers to a state in which the polymer exists in the gap between the conductor strands, Also, when the conductor strands are compressed in the radial direction so as to be in close contact with each other, the state in which the polymer exists so as to be in close contact with the inner peripheral surface of the conductor strands arranged on the circumference Point to.

Various types of thermosetting polymers are conventionally known. For example, hard thermosetting polymers such as epoxy resin, phenol resin, and melamine resin, and polyolefin-based polymers used as insulating materials for electric wires are used. A soft thermosetting polymer obtained by compounding a crosslinking component with a soft polymer such as resin, fluorine rubber, silicone rubber, or ethylene-propylene rubber and curing by crosslinking is mentioned. When considering the flexibility and processability, it is desirable to use a soft thermosetting polymer obtained by blending a crosslinking component with a soft polymer and curing by crosslinking. These may be appropriately selected in consideration of the usage conditions (use, required functions, and the like) of the electric wire obtained by the present invention, the type of an insulator described later, a method of forming an airtight portion (a curing method, and the like), and the like. In addition, compounding chemicals such as a flame retardant, a coloring agent, a processing aid, and an antioxidant can be appropriately added according to the use conditions of the electric wire. When a crosslinking treatment is performed on the insulator, a filler obtained by blending a crosslinking component with the soft polymer is used as the filler, and the filler is crosslinked by heat when extruding and crosslinking the insulator. The steps required for curing of the resin can be shortened.

It is preferable that the filler contains an expansion component so that the filler expands when forming the airtight portion so as to surely enter the gap between the conductor wires. As the expansion component, various types are conventionally known, for example, a method of injecting a nitrogen gas or the like at the time of molding a filler and physically foaming the same, or azodicarbonamide, azobis A method of blending a foaming agent such as isobutyronitrile, dinitrosopentamethylenetetramine, P, P'-oxybisbenzenesulfonylhydrazide, P-toluenesulfonylhydrazide, and chemically foaming is used. These types and addition amounts may be appropriately selected and adjusted in consideration of the use conditions (use, required functions, and the like) of the electric wire obtained by the present invention. In the case where the insulator is subjected to a crosslinking treatment, a foaming agent is used as an expanding component, and the filler is expanded by heat generated when the insulator is extruded and crosslinked, thereby performing a process necessary for forming an airtight portion. Can be shortened.

In the present invention, the filler made of the above-mentioned thermosetting polymer and the conductive strand are twisted at least so that the conductive strand is disposed on the outermost layer to form a stranded conductor. At this time, it is conceivable to twist the conductor strands while the thermosetting polymer remains uncured, and compress the conductor strands arranged in the outermost layer in the radial direction so that the conductor strands are in close contact with each other. . By doing so, the conductor strands bite into the filler having plasticity when forming the stranded conductor, and when forming an airtight portion in the stranded conductor, the filler is cured by heating the filler, Since the expanded thermosetting polymer can be prevented from flowing out of the gap between the conductor strands, it is not necessary to remove the resin material attached to the conductor strands at the time of processing a terminal or the like. The compression processing of the conductor strand may not be performed at the time of forming the stranded conductor, but may be performed while applying a predetermined pressure at the time of forming the hermetic portion after the formation of the stranded conductor.

The airtight portion is for preventing oil and water from entering the inside of the electric wire due to the capillary phenomenon, and preventing oil and water entering the inside of the electric wire from leaking from the end portion of the electric wire. By hardening and expanding the filler,
The stranded conductor is formed on at least a part (a part, a plurality of parts, or all) in a longitudinal direction. Whether the hermetic portion is formed in a part of the stranded conductor, in a plurality of portions, or in the entire portion is selected in consideration of the use conditions (use, required functions, etc.) of the electric wire obtained by the present invention. And is not particularly limited.

The method for forming the hermetic portion is not particularly limited, either.
Various methods can be considered, such as a method of forming an airtight portion at the same time as the crosslinking of the insulator by using heat at the time of crosslinking of the insulator, and a method of heating at the time of processing the end of the electric wire. When a cross-linking treatment is performed, it is preferable that the filler is cured and expanded by utilizing heat at the time of cross-linking the insulator.

The insulator is formed by extrusion-coating various known insulating coating materials on a stranded conductor using a known extruder. Depending on the type of insulating coating material, the insulator is appropriately crosslinked. Processing is performed. The type of the insulating coating material is selected in consideration of the usage conditions (application, required functions, and the like) of the electric wire obtained by the present invention, and is not particularly limited.

[0019]

EXAMPLES Examples of the present invention will be described below together with comparative examples.

EXAMPLE 1 A 1.2 mm diameter filler made of a fluororubber mixture containing nine tinned soft copper wires (TA) having a wire diameter of 0.6 mm and 2.0 parts by weight of a foaming agent (azodicarbonamide). Are twisted at a pitch of 18.5 mm so that the conductor strands are arranged in the outermost layer, and then compressed in the radial direction so that the conductor strands are in close contact with each other, and a stranded conductor having a finish outer diameter of 2.3 mm is formed. Was formed. Next, an insulator made of a fluororubber mixture was extrusion-coated on the stranded conductor at a thickness of 0.5 mm and crosslinked by a known method to obtain an electric wire having a finished outer diameter of 3.3 mm. Note that the hermetic portion was formed by simultaneously curing and foaming the filler made of the fluororubber mixture by the heat of crosslinking the insulator. FIG. 1 is a cross-sectional view of the hermetic wire obtained in this manner. Here, reference numeral 1 denotes a stranded conductor, reference numeral 1a denotes a conductor strand, reference numeral 1b denotes an airtight portion (cured material of a filler), and reference numeral 2 denotes an insulator.

Comparative Example In this example, 47 tin-plated annealed copper wires (TA) having a wire diameter of 0.26 mm at a pitch of 60 mm were used without using the filler made of the fluororubber mixture containing the foaming agent used in the examples. Twisted to form a stranded conductor. Next, an insulator made of a fluororubber mixture is extrusion-coated on the stranded conductor with a thickness of 0.5 mm and crosslinked by a known method to finish 3.1 mm in outer diameter.
I got the wires. FIG. 2 is a sectional view of the hermetic electric wire obtained in this manner. Here, reference numeral 1 indicates a stranded conductor, and reference numeral 2
Is an insulator.

Here, the above two types of electric wires are used as samples.
The airtightness, oil leakage, and terminal workability (terminal workability) were evaluated. The evaluation method is as follows. The evaluation results are shown in Table 1.

Airtightness One end of the sample cut to a length of 200 mm
An air pressure of Pa was applied, and the amount of air leaked from the other end of the sample was measured for 10 minutes. Oil Leakage One end of a sample cut to a length of 500 mm was immersed in oil, a pressure of 0.196 MPa was applied to the oil surface, and the amount of oil leaked from the other end of the sample in 24 hours was measured. The test oil used was Nissan Matic Fluid D oil. Terminal Workability (Terminal Workability) For the sample according to the present example, the insulator at the portion where the airtight portion was formed was stripped to a width of 20 mm, and the state of attachment of the filler and the insulating coating material to the surface of the stranded conductor was visually observed. Confirmed. In the sample according to the comparative example, the insulator at an arbitrary position in the length direction was stripped by 20 mm in width, and the state of adhesion of the insulating coating material to the surface of the stranded conductor was visually checked.

[0024]

[Table 1]

As a result, air leakage and oil leakage were confirmed in the electric wire of the comparative example, whereas no air leakage and oil leakage were confirmed in the electric wire according to the present embodiment. That is, it was found that the electric wire according to the present example is an electric wire that can surely prevent oil, water, and the like from entering the inside of the electric wire due to the capillary phenomenon and leaking from the end of the electric wire.
In addition, the wire according to the present embodiment has a terminal workability (terminal workability).
Also, no resin was attached to the surface of the stranded conductor at all, and the wire had the same workability as the electric wire of the comparative example. Furthermore,
In the electric wire according to the present embodiment, the hermetic portion is formed simultaneously with the crosslinking of the insulator, so that the productivity is the same as the electric wire of the comparative example.

[0026]

As described in detail above, the hermetic electric wire of the present invention is provided with an hermetic portion formed from a cured thermosetting polymer on at least a part of the length of the stranded conductor. In addition, it is possible to reliably prevent oil, water, and the like from entering the inside of the electric wire due to the capillary phenomenon and leaking from the end of the electric wire. In addition, the end processing is easy, and the wire can be easily manufactured by the same method as that for manufacturing a normal electric wire, so that it can be provided at low cost. Therefore, for example, it can be suitably used in a wide range of applications, such as a lead wire arranged in an oil case of an automatic transmission of an automobile.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and is a cross-sectional view of an airtight electric wire.

FIG. 2 is a view showing a comparative example, and is a cross-sectional view of an electric wire in which an airtight portion is not formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Twisted wire conductor 1a Conductor strand 1b Airtight part (hardened | cured material of filler) 2 Insulator

Claims (4)

[Claims] 1. An airtight wire comprising a stranded conductor having an airtight portion formed in at least a part of a length direction thereof and an insulator coated on an outer periphery of the stranded wire conductor. Conductor strands and filler made of thermosetting polymer are essential components, and conductor strands are arranged in the outermost layer,
An airtight electric wire, wherein a cured product of the filler penetrates between the conductor strands in an airtight portion of the stranded conductor. 2. The hermetic electric wire according to claim 1, wherein the conductor wires arranged in the outermost layer of the stranded conductor are radially compressed so as to be in close contact with each other. . 3. The hermetic electric wire according to claim 1, wherein the filler contains an expansion component. 4. The method for producing an airtight electric wire according to claim 1, wherein the filler is plastically deformable when the stranded conductor is twisted. The method of manufacturing an airtight electric wire, wherein the step of curing the filler is performed under the condition that an expansion component in the filler acts while the insulator is coated on the stranded conductor.