WO2009096591A1

WO2009096591A1 - Crimp terminal

Info

Publication number: WO2009096591A1
Application number: PCT/JP2009/051827
Authority: WO
Inventors: Tadahisa Sakaguchi; Yasumichi Kuwayama
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2008-01-28
Filing date: 2009-01-28
Publication date: 2009-08-06
Anticipated expiration: 2010-07-28
Also published as: JP2009176672A; JP5030232B2

Abstract

A crimp terminal for press-clamping an aluminum wire having a conductive part which is configured by a plurality of wire elements formed of aluminum or aluminum alloy twisted together, includes a barrel part which press-fastens the conductive part. A coating film, having agglutinating function against the aluminum and aluminum alloy, is formed on a contact surface of the barrel so as to bring into contact with the conductive part. At least one groove, extending in a direction intersecting with an axial direction of the conductive part, is formed on the contact surface of the barrel. A pair of slanted parts, extending in the axial direction of the conductive part, are arranged at both sides of the at least one groove on the contact surface of the barrel. The pair of slanted parts are slanted so as to have falling gradients in a direction away from the at least one groove.

Description

DESCRIPTION

CRIMP TERMINAL

Technical Field

The present invention relates to a crimp terminal for an aluminum wire to be press-clamped to the aluminum wire having a conductive part which is configured by a plurality of wire elements formed of aluminum or aluminum alloy twisted together.

Background Art

Electric wires formed of copper are generally used in wire harnesses which are arranged in a vehicle such as an automobile. When the wire harnesses are connected to each other, or the wire harnesses are connected to an on-vehicle apparatus, terminals are attached to the copper wires of the wire harnesses. The terminals of this type are generally attached to the copper wires by press-clamping.

The terminal to be press-clamped to the copper wire is formed, for example, by stamping a sheet material having electrical conductivity such as copper alloy into a determined shape, and then, by subjecting it to folding work.

This terminal has a barrel which is typically formed in a substantially U-shape in cross section. The barrel embraces a conductive part of the copper wire which is composed of a plurality of wire elements formed of copper and twisted together, and attached to the conductive part by crimping. In this manner, the terminal is press-clamped to the copper wire.

By the way, in recent years, attention has been paid to use of an aluminum wire, considering weight reduction and easiness in recycling, in addition to shortage of copper resources. However, an oxidation layer formed on a surface is thicker in aluminum than in copper. For this reason, contact resistance between the conductive part of the aluminum wire and the barrel of the terminal tends to become relatively high.

In order to lower the contact resistance, a method of enhancing compression rate of the conductive part by tightly crimping the barrel to the conductive part has been known. According to this method, the oxidation layers of the wire elements which compose the conductive part are broken, and the contact resistance between the conductive part and the barrel is lowered. In this specification, the compression rate is defined as a ratio between a sectional area of the conductive part before press-clamping and the sectional area after the press-clamping.

However, as the compression rate is enhanced, stress exerted on the conductive part is also enhanced. Because aluminum has inferior mechanical strength as compared with copper, press-clamping strength between the conductive part and the barrel in the aluminum wire is remarkably deteriorated, in case where an excessive stress is exerted on the conductive part.

For the purpose of reducing the contact pressure and securing the sufficient press-clamping strength, various methods concerning the press-clamping between the aluminum wire and the terminal have been heretofore proposed. For example, it is proposed to form a plurality of concave grooves on a contact surface of the barrel which is brought into contact with the conductive part (for example, see JP-A-2007-173215). In this case, the conductive part enters into the concave grooves, and the oxidation layers on the surfaces of the wire elements are broken, whereby the contact resistance is reduced. In addition, escape of the conductive part is prevented. It is also proposed to scatter powder which is softer than the conductive part on the contact surface of the barrel thereby to fix the conductive part to the contact surface of the barrel by agglutination (for example, JP-A-8-321330).

Disclosure of Invention Technical Problem In case of fixing the conductive part to the contact surface of the barrel by agglutination, it is also necessary to break the oxidation layers on the surfaces of the wire elements for enabling new surfaces of the wire elements to be exposed. Although it is possible to break the oxidation layers on the surfaces of the wire elements, by forming the concave grooves on the contact surface of the barrel, the oxidation layers cannot be sufficiently broken, because breaks of the oxidation layers occur mainly in edge parts of the concave grooves. Moreover, in order to sufficiently break the oxidation layers by the conventional barrel which is provided with the concave grooves on the contact surface thereof, it is necessary to enhance the compression rate of the conductive part. In this case, however, deterioration of the press-clamping strength becomes a problem.

The invention has been made in view of the above described circumstances, and it is an object of the invention to provide a crimp terminal for an aluminum wire which can satisfy both decrease of contact resistance and securance of press-clamping strength between a conductive part of the aluminum wire and a barrel of the terminal.

Technical Solution The above described object is attained by the crimp terminal for the aluminum wire as described in the following items (1) and (2).

(1 ) A crimp terminal for press-clamping an aluminum wire having a conductive part which is configured by a plurality of wire elements formed of aluminum or aluminum alloy twisted together, the crimp terminal comprising: a barrel part which press-fastens the conductive part, wherein a coating film, having agglutinating function against the aluminum and aluminum alloy, is formed on a contact surface of the barrel so as to bring into contact with the conductive part; wherein at least one groove, extending in a direction intersecting with an axial direction of the conductive part, is formed on the contact surface of the barrel; wherein a pair of slanted parts, extending in the axial direction of the conductive part, are arranged at both sides of the at least one groove on the contact surface of the barrel; and wherein the pair of slanted parts are slanted so as to have falling gradients in a direction away from the at least one groove..

(2) A crimp terminal for an aluminum wire as described in the above item (1 ), the coating film is a tin plated coating film.

According to the crimp terminal for the aluminum wire having the structure as described in the above item (1), the conductive part which is compressed with the barrel fitted thereto by crimping enters into the groove, and is extended to both sides of the groove from the area where it has entered into the groove, thereby to slide along the slanted parts which are formed at both sides of the groove. Then, the oxidation layers on the surfaces of the wire elements which compose the conductive part are broken by friction, while the wire elements slide along the slanted faces, and the new born surfaces are exposed on the respective wire elements. In this manner, it is possible to sufficiently break the oxidation layers of the wire elements and to expose the new bom surfaces, without excessively enhancing the compression rate of the conductive part. Moreover, the coating film having the agglutinating function against aluminum and aluminum alloy is formed on the contact surface of the barrel, and the agglutination occurs between the new born surfaces exposed on the respective wire elements and the coating film, whereby the favorable contact resistance and press-clamping strength can be obtained.

Advantageous Effects According to the crimp terminal for the aluminum wire of the invention, it is possible to satisfy both decrease of the contact resistance and securance of the press-clamping strength between the conductive part of the aluminum wire and the barrel of the terminal.

Brief Description of Drawings

Fig. 1 is a perspective view of a crimp terminal for an aluminum wire according to an embodiment of the invention.

Fig. 2 is a sectional view showing the crimp terminal in Fig. 1 in a state press-clamped to the aluminum wire. Fig. 3 is a perspective view of a modification of the crimp terminal in

Fig. 1.

Best Mode for Carrying Out the Invention

Now, a preferred embodiment of the crimp terminal for the aluminum wire according to the invention will be described in detail referring to the drawings.

As shown in Fig. 1 , an aluminum wire 1 has a conductive part 2 which is configured by a plurality of wire elements 3 formed of aluminum or aluminum alloy twisted together. An outer periphery of the conductive part 2 is covered with a sheath 4 which is formed of insulating material. The sheath 4 is removed from the aluminum wire 1 by a determined length in a terminal end part of the aluminum wire 1 , and the conductive part 2 is exposed. A terminal 10 to be press-clamped to the aluminum wire 1 is press-clamped to this terminal end part. As the aluminum alloy, an alloy of aluminum and iron can be used as an example. The alloy of aluminum and iron is preferably used, since it is excellent in strength (especially, tensile strength), as compared with simple aluminum.

The terminal 10 has a connecting part 11 to be connected with a mating terminal (not shown) at a distal end side thereof, and a barrel 12 to be fitted to the aluminum wire 1 by crimping at a base end side thereof. The barrel 12 is provided with a wire barrel 13 to be fitted by crimping to the conductive part 2 of the aluminum wire 1 at a distal end side thereof and an insulation barrel 14 to be fitted by crimping to the sheath 4 of the aluminum wire 1 at a base end side thereof.

The wire barrel 13 is formed in a substantially U-shape in cross section, having a bottom plate part 20 on which the conductive part 2 which is exposed in the terminal end part of the aluminum wire 1 is placed, and a pair of crimping pieces 21 continued from the bottom plate part 20 so as to clamp the conductive part 2 which is placed on the bottom plate part 20 from both sides. The wire barrel 13 embraces therein the conductive part 2 in the terminal end part, and fitted to this conductive part 2 by crimping.

The insulation barrel 14 is formed in a substantially U-shape in cross section in the same manner as the wire barrel 13, having a bottom plate part 22 on which the sheath 4 which remains in the terminal end part of the aluminum wire 1 is placed, and a pair of crimping pieces 23 continued from the bottom plate part 22 so as to clamp the sheath 4 which is placed on the bottom plate part 22 from both sides. The insulation barrel 14 embraces therein the sheath 4 in the terminal end part, and fitted to the sheath 14 by crimping. It is to be noted that the bottom plate part 22 of the insulation barrel 14 is continued from the bottom plate part 20 of the wire barrel 13.

The wire barrel 13 which embraces the conductive part 2 in the terminal end part is fitted to this conductive part 2 by crimping, and the insulation barrel 14 which embraces the sheath 4 in the terminal end part is fitted to this sheath 4 by crimping, whereby the terminal 10 is press-clamped to the aluminum wire 1.

On an inner surface of the wire barrel 13, that is, a contact surface of the wire barrel 13 to be brought into contact with the conductive part 2, there are formed at least one groove 24 which extends in a direction intersecting with an axial direction of a press-clamping portion of the conductive part 2 to which the wire barrel 13 is fitted by crimping, and a pair of slanted parts 25a, 25b which respectively extend downwardly from the groove 24 toward the distal end side and the base end side of the press-clamping portion of the conductive part 2. The groove 24 and the slanted parts 25a, 25b are provided on the contact surface of the bottom plate part 20.

Although the groove 24 extends in the direction perpendicularly intersecting with the axial direction of the press-clamping portion of the conductive part 2 in the embodiment as shown in Fig. 1 , the groove 24 may extend in a direction diagonally intersecting with the axial direction. Moreover, although the groove 24 and the slanted parts 25a, 25b are provided within a range of the bottom plate part 20 of the wire barrel 13 in the embodiment as shown in Fig. 1 , they may be provided over the bottom plate part 20 and a pair of the crimping pieces 21. Further, although the only one groove 24 is shown in Fig. 1 , a plurality of the grooves 24 may be formed.

In addition, a coating film having agglutinating function against aluminum and aluminum alloy is formed at least on the contact surface of the wire barrel 13. Such coating film is formed of metal, for example, which is softer than aluminum and aluminum alloy, and preferably includes a tin plated coating film. Preferably, the coating film has a thickness of 1.5μm to 4.0μm.

The terminal 10 having the above described structure is formed by stamping a sheet of sheet material having electrical conductivity such as copper alloy having tin plating on its surface into a determined shape, and by subjecting it to folding work.

As shown in Fig. 2, the wire barrel 13 is fitted to the conductive part 2 by crimping, whereby the conductive part 2 is compressed, and the wire elements 3 which compose the conductive part 2 enter into the groove 24 formed on the contact surface of the wire barrel 13. Then, the wire elements 3 are extended in the axial direction to both sides of the groove 24 from the areas where they have entered into the groove 24, as base points, and slide along the slanted parts 25a, 25b which are formed at the both sides of the groove 24. The oxidation layers on the surfaces of the wire elements 3 in the areas where the wire elements 3 slide along the slanted parts 25a, 25b are broken by friction between the oxidation layers and the slanted parts 25a, 25b, and in these areas, new born surfaces, that is, a matrix of aluminum or aluminum alloy is exposed.

Then, friction under face pressure occurs between the coating film formed on the contact surface of the wire barrel 13 and the new born surfaces exposed on the respective wire elements 3, and agglutination occurs between them. Because of this agglutination, the coating film on the wire barrel 13 and the new born surfaces of the respective wire elements 3 are bonded to each other at an atomic level. In this manner, a favorable contact resistance and bonding strength can be obtained.

As described above, according to the crimp terminal for the aluminum wire in this embodiment, the conductive part 2 which is compressed with the wire barrel 13 fitted by crimping enters into the groove 24, and is extended to both sides of the groove 24 from the area where it has entered into the groove 24, as a base point, thereby to slide along the slanted parts 25a, 25b which are formed at the both sides of the groove 24. Then, the oxidation layers on the surfaces of the wire elements 3 which compose the conductive part 2 are broken by the friction, while the wire elements 3 slide along the slanted parts 25a, 25b, and the new born surfaces are exposed on the respective wire elements 3. In this manner, it is possible to sufficiently break the oxidation layers of the wire elements 3 and to expose the new born surfaces, without excessively enhancing the compression rate of the conductive part 2. Moreover, the coating film having the agglutinating function against aluminum and aluminum alloy is formed on the contact surface of the wire barrel 13, and the agglutination occurs between the new born surfaces exposed on the respective wire elements 3 and the coating film, whereby the favorable contact resistance and press-clamping strength can be obtained.

It is to be noted that the invention is not limited to the above described embodiment, but various modifications, improvements and so on can be appropriately made. In addition, shapes, sizes, numbers, modes, positions to be arranged, and so on in the above described embodiment are optional, but not limited, provided that the invention can be attained.

For example, as shown in Fig. 3, the groove 24, and the slanted parts 25a, 25b may be provided in such a manner that they protrude from the contact surface of the bottom plate part 20 of the wire barrel 13 as a whole.

The present application is based on Japanese Patent Application No. 2008-016603 filed on January 28, 2008, the contents of which are incorporated herein for reference.

Industrial Applicability

The crimp terminal for the aluminum wire of the invention can provide to satisfy both decrease of the contact resistance and securance of the press-clamping strength between the conductive part of the aluminum wire and the barrel of the terminal.

Claims

1. A crimp terminal for press-clamping an aluminum wire having a conductive part which is configured by a plurality of wire elements formed of aluminum or aluminum alloy twisted together, the crimp terminal comprising: a barrel part which press-fastens the conductive part, wherein a coating film, having agglutinating function against the aluminum and aluminum alloy, is formed on a contact surface of the barrel so as to bring into contact with the conductive part; wherein at least one groove, extending in a direction intersecting with an axial direction of the conductive part, is formed on the contact surface of the barrel; wherein a pair of slanted parts, extending in the axial direction of the conductive part, are arranged at both sides of the at least one groove on the contact surface of the barrel; and wherein the pair of slanted parts are slanted so as to have falling gradients in a direction away from the at least one groove.

2. The crimp terminal, according to claim 1 , wherein the coating film is a tin plated coating film.