JP2007299659A - Covered wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat cable type covered wire in which mechanical strength against screw-mounting and repetitive bending is elevated, and reliability as a ground wire and a high voltage wire is elevated. <P>SOLUTION: The covered wire GS is provided with a flat conductor 1 having a crimping part 12 of a large width at least at one end of the conductive part 11 which is a thin metal plate of a small width, and an insulation cover 2 that covers the conductive part 11, and a screw-mounting hole 13 is bored in the crimping part 12, while the insulation cover 2 is extended to a position where the end part is in the vicinity or in contact with the screw-mounting hole 13. When the screw 3 is mounted on the crimping part 12, a part of the screw 3 becomes in a state contacted with the insulation cover 2, therefore, bending of the covered wire GS in an acute angle can be prevented, and fracture due to metal fatigue can be suppressed since concentration of bending stress on a part of the flat conductor 1 does not occur. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coated electric wire suitable for use in a ground wire or a high voltage wire of an electronic device, and more particularly to a coated electric wire configured as a flat cable.

  Insulated wires are used as ground wires and high-voltage wires for grounding electronic equipment. Conventionally, metal braided wires are formed into thin strips, and crimped terminals with metal plates processed at both ends are attached by welding or caulking, etc. Further, a metal braided wire coated with an insulating tube or the like has been proposed. The crimp terminal is provided with a screw mounting hole, and is connected to an electronic device by a screw. Although this coated electric wire has high mechanical strength and high electric withstand voltage, the metal braided wire is thinned because the metal wires constituting the braided wire overlap each other. There is a problem that it is difficult to form, and further, it is difficult to bend because an insulating tube is placed thereon, so that it is difficult to attach the electronic device to a place where there is little space.

In contrast to such a covered electric wire using a metal braided wire, the present applicant has previously proposed a covered electric wire constituted by a flat cable. FIG. 6A shows a covered electric wire GS1 proposed in Patent Document 1, which is configured as a grounding strap. The covered electric wire GS1 is formed by pressing a thin metal plate such as a copper foil to have a narrow conductive portion 111 and a slightly wide crimping portion 112 integrally provided at both ends of the conductive portion 111. The conductive portion 111 of the flat conductor 101 is covered with an insulating coating 102 made of an insulating resin film. The insulating coating 102 is obtained by bonding two thin resin films so that the flat conductor 101 is sandwiched in the thickness direction, and then bonding them together by heat welding or using an adhesive. Further, the crimping portion 112 is provided with a screw mounting hole 113. As shown in FIG. 6B, this covered electric wire GS1 is connected to a part of the electronic device ED by fastening the crimping portion 112 to a part of the electronic device ED with the screw 103 inserted into the screw mounting hole 113, and the electronic device ED is grounded. To do. Since this coated wire GS1 can be formed with a very small thickness, it can be easily bent in the thickness direction and can be attached to a place where there is little space in the electronic device. In addition, there exists a technique of patent document 2, for example as a manufacturing technique of this kind of flat cable type covered electric wire.
Design Registration No. 1237251 JP 2004-146206 A

  In the covered electric wire GS1 of Patent Document 1, the crimping portion 112 of the flat conductor 101 is not covered with the insulating coating 102. Therefore, a fastening torque applied to the screw when the crimping portion 112 is attached to the electronic device with the screw 103 is applied to the surface of the crimping portion 112, and this force acts as a shearing force on the thin crimping portion 112, Damage such as a slit entering the portion 112 may occur. In addition, as shown in FIG. 6C, when the coated electric wire GS1 is bent in a state where the covered electric wire GS1 is attached to the electronic device ED with the screw 103, the portion covered with the insulating coating 102 has a strength against bending. Although high, bending stress concentrates on a portion where the insulating coating 102 does not exist, particularly on a boundary region between the crimping portion 112 and the conductive portion 111 exposed from the insulating coating 102, and the conductive portion 111 bends at an acute angle in this portion. It will be. When the conductive portion 111 is bent at an acute angle in this manner, the mechanical strength of this portion is reduced, and particularly when the conductive portion 111 is bent a plurality of times, the portion may be broken due to metal fatigue.

  An object of the present invention is to provide a flat cable type covered electric wire with improved mechanical strength against screw mounting and repeated bending, and improved reliability as a ground wire or a high voltage wire.

  The present invention is a coated electric wire comprising a flat conductor having a crimped portion having a large width dimension at least at one end of a narrow conductive portion formed of a thin metal plate, and an insulating coating covering the conductive portion of the flat conductor. Then, a screw attachment hole is opened in the crimping portion, and the insulating coating is extended to a position where the end portion is close to or in contact with the screw attachment hole. In the present invention, the flat conductor has crimp portions at both ends of the conductive portion, and the insulating coating is extended to a position where both end portions in the length direction are close to or in contact with the screw mounting holes. That is, both end portions of the insulating coating are configured to be in contact with a head portion of a screw inserted through the screw mounting hole or a washer inserted through the screw.

  According to the coated electric wire of the present invention, since the insulating coating is provided in a state extending to the crimping portion of the flat conductor, when the screw is attached to the crimping portion, the screw is in contact with the insulating coating, and the screw The fastening force when fastening is not directly transmitted to the conductor, and damage to the crimping portion is prevented. In addition, when the covered electric wire is bent, the flat conductor is bent in the vicinity of the screw of the crimping portion, that is, the portion where the insulation coating exists, so that the covered electric wire is prevented from being bent at an acute angle, and the flat electric conductor is prevented. Bending stress is prevented from concentrating on a part of the metal, and fracture due to metal fatigue is suppressed.

  Next, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of a covered electric wire according to the present invention, and FIGS. 2A to 2C are a plan view, an AA line enlarged sectional view, and a BB line enlarged sectional view. Example 1 is an example of a covered electric wire GS in which the present invention is configured as a grounding strap for grounding an electronic device. The covered electric wire GS is a flat conductor 1 formed by pressing a thin metal plate such as a copper foil. And an insulating coating 2 that covers the flat conductor 1. The flat conductor 1 is a so-called elongate conductive portion 11 having a required width and length, and a crimping portion 12 that is integrally formed at both ends of the conductive portion 11 and has a larger width dimension than the conductive portion 11. It is configured in a dogbone shape. The crimping part 12 is formed in an arc shape with a required curvature at both inner side parts 12a which become a boundary region with the conductive part 11. Also, the outer end edges are slightly rounded at the corners, and screw attachment holes 13 for attaching the covered electric wire to the electronic device are opened at the centers of both crimping portions.

  Here, the insulating coating 2 is composed of two insulating resin films 21, which face each other so that the flat conductor 1 is sandwiched between the insulating resin films 21 in the thickness direction, and the two are bonded by an adhesive. And integrated. Alternatively, both insulating resin films 21 may be integrated by thermocompression bonding. Furthermore, the insulating film resin film having a cylindrical shape may be crushed and flattened to form an insulating coating. In Example 1, since the two insulating resin films 21 have a width dimension equal to the width dimension of the crimping part 12 of the flat conductor 1, the conductive parts of the flat conductor 1 are bonded when the two insulating resin films 21 are bonded together. 11, both insulating resin films 21 are in direct contact with each other in a region along both sides of the substrate 11 and are bonded or welded in the contacted region. The insulating coating 2 is formed to a length that reaches the screw mounting holes 13 provided in the crimping portions 12 at both ends of the flat conductor 1, thereby the boundary between the conductive portion 11 and the crimping portion 12 of the flat conductor 1. The region of the both side portions 12 a that is a region is covered with an insulating coating 2. Here, both end portions 2 a of the insulating coating 2, that is, both end portions of the insulating resin film 21, are formed in a length that overlaps a part of each screw mounting hole 13, and then in an arc shape along the periphery of the screw mounting hole 13. Notches have been removed.

  When connecting the covered electric wire GS of Example 1 to an electronic device, the crimping parts 12 at both ends are attached to the electronic device ED with the screws 3 shown in FIG. FIG. 3A is an enlarged side view of the attached state. The screw 3 through which the washer 31 is inserted is inserted into the screw mounting hole 13 (see FIGS. 1 and 2) of the crimping portion 12, and the electronic device ED is inserted by the screw 3. Fasten to the chassis or panel. When the screw 3 is fastened, the crimp portion 12 of the covered wire GS is slightly deformed in the thickness direction, and the back surface of the crimp portion 12 is brought into contact with and electrically connected to the conductive portion of the electronic device ED. At the same time, the washer 31 partially contacts the surface of the crimping part 12 and is electrically connected to the conductive part of the electronic device ED via the screw 3. Torque when the screw 3 is fastened is transmitted from the screw 3 to the covered wire GS via the washer 31, but the washer 31 is also in contact with the surface of the insulating coating 2 at a part of the circumference, and is generated by fastening the screw 3. Torque is transmitted to the insulating coating 2, and the torque is absorbed when the insulating coating 2 is compressed and deformed in the thickness direction, and the torque transmitted to the crimping portion 12 is reduced to suppress damage at the crimping portion 12. Become.

  Further, as shown in FIG. 3B, when the covered electric wire GS is attached to the electronic device ED, or after being attached, when the covered electric wire GS is bent in the plate thickness direction as indicated by an arrow in the drawing, In this case, bending stress is applied to the edge of the head of the screw 3, that is, the portion where the washer 31 is in contact with the insulating coating 2, but the coated wire is bent at an acute angle due to the thickness and rigidity of the insulating coating 2. As a result, the radius of curvature of the covered electric wire GS increases. Thereby, the fracture | rupture by the metal fatigue of the flat conductor 1 with respect to the repeated bending in a covered electric wire is prevented.

  FIG. 4 is a diagram showing the results of a bending test for the covered electric wire GS of Example 1 and the covered electric wire GS1 of Patent Document 1. Here, in the covered electric wire of Example 1, as shown in FIG. 4A, the thickness T of the flat conductor 1 is 0.1 mm, the width dimension W1 of the conductive portion 11 is 4.5 mm, and the width dimension W2 of the crimping portion 12. Is 10 mm. Further, as shown in the figure, the covered wire GS of Example 1 has a plurality of curvature radii Rx of the side portions 12a of the boundary region between the conductive portion 11 and the crimping portion 12 formed in R1, R3, R5, and R7, respectively. Different covered electric wires were prepared as Sample R1, Sample R3, Sample R5, and Sample R7. Here, R1 means a radius = 1 mm, and so on. The reference product is the covered electric wire GS1 of Patent Document 1 shown in FIG. 6A, and the flat conductor has the same thickness and width as those in the first embodiment. Five samples are prepared for each of the reference products and the samples R1, R3, R5, and R7 of the covered wire GS of the present invention, and one crimping portion 12 is connected to the test base EB with the screw 3 as shown in FIG. 1 is a test in which the coated wire is bent in one direction at approximately 90 degrees by applying a force to the substantially central portion in the length direction of the covered wires GS and GS1 as indicated by an arrow, and then bent at 90 degrees in the opposite direction. The number of times until the covered electric wire broke was measured. In addition, since it is difficult to visually check from the appearance when the breakage of the covered electric wire occurs inside the insulating coating 2, the electric resistance between the crimping portions 12 at both ends is sequentially measured with an electric resistance meter as the bending test proceeds. Then, it was determined that the time when the resistance value deteriorated was broken.

  As a result of the test, as shown in the table of FIG. 4C, the reference product was broken by an average of 39 reciprocal bendings, whereas the sample R1 of the covered wire GS of Example 1 was not broken up to an average of 208 reciprocations. It has been found. In addition, it was measured that the sample R3 did not break until 268 reciprocations, the sample R5 did 334 reciprocations, and the sample R7 did not break until 368 reciprocations. From this, it was confirmed that the breaking strength against bending of the covered electric wire of Example 1 was increased, and in particular, it was confirmed that the breaking strength was higher as the radius of curvature of the boundary region between the crimping portion and the conductive portion was larger.

  Here, in the present invention, since the head of the screw 3 or the washer 31 may overlap with a part of the insulating coating 2 when the screw 3 is attached to the crimping portion 12, the flat conductor 1 and the insulating coating The shape of 2 is not limited to the configuration of the first embodiment. For example, for the flat conductor 1, as shown in FIG. 5A, the crimping portion 12 may be formed in a circular shape. Further, the insulating coating 2 preferably has the same width dimension as that of the crimping part 12 as in the first embodiment, but may be slightly larger than the width dimension of the crimping part 12 as shown in FIG. Further, the end 2a of the insulating coating 2 may be cut out along the periphery of the screw mounting hole 13 as shown in FIG. 5C. In this case, the screw mounting hole 13 and the insulating coating 2 are connected to each other. It can be processed at the same time. Furthermore, as shown in FIG. 5 (d), the end portion of the insulating coating 2 may be formed in a straight line shape so as to be in contact with one edge portion of the screw mounting hole 13. In this case, as shown in FIG. Thus, since it is not necessary to cut out the end of the insulating coating 2 in an arc shape, the processing of the insulating coating is facilitated.

  In Example 1, the flat conductor is formed of copper foil, but other metal foil or metal thin plate may be used as long as it can be used as an electric wire. Moreover, the covered electric wire which has a crimping | compression-bonding part only in one side of the length direction of a flat conductor may be sufficient as this invention. For example, it is also applicable to a covered electric wire in which the other end portion of the flat conductor is fitted to an electronic device or the like for electrical connection, or a covered electric wire in which the other end portion is integrated with the electronic device by welding or the like. it can.

1 is an external perspective view of a covered electric wire of Example 1. FIG. It is a top view of the covered electric wire of Example 1, an AA line expanded sectional view, and a BB line expanded sectional view. It is an enlarged side view which shows the connection state of the covered electric wire of Example 1. FIG. It is a figure explaining the bending test of Example 1 and the conventional covered electric wire. FIG. 6 is a plan view of a part of various modifications of the first embodiment. It is an enlarged side view which shows the top view and connection state of the conventional covered electric wire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Flat conductor 2,102 Insulation coating 3,103 Screw 11,111 Conductive part 12,112 Crimp part 13,113 Screw attachment hole 21 Insulating resin film GS, GS1 Coated electric wire (Granding strap)
ED electronic equipment

Claims (3)

  A coated electric wire comprising a flat conductor having a crimped portion having a large width dimension at least at one end of a narrow conductive portion formed of a thin metal plate, and an insulating coating covering the conductive portion of the flat conductor. A screw attachment hole is opened in the crimping portion, and the insulating coating is extended to a position where an end portion in the length direction is close to or in contact with the screw attachment hole.   2. The flat conductor according to claim 1, wherein crimp portions are provided at both ends of the conductive portion, and both end portions in the length direction of the insulating coating are extended to positions close to or in contact with the screw mounting holes. The covered electric wire described. 3. The covered electric wire according to claim 1, wherein an end portion of the insulating coating in a length direction is in contact with a head portion of a screw inserted into the screw mounting hole or a washer inserted into the screw.

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