Terminated electric wire

Abstract

This terminated electric wire is composed of a loop at the tip and stranded wires extending from a base portion of the loop. At a molten portion of the base portion of the loop, two stranded wires cross each other, and the stranded wires are fused so that strands constituting the stranded wires are fixed together and integrated. In diffusion-bonded portions on both sides of the base portion of the loop, the strands are diffusion-bonded to each other while maintaining the shape of the strands. In the part from the tip of the loop to the front of the diffusion-bonded portions, the strands of the stranded wires are independent from each other and are not bonded to each other. Further, the inner peripheral surface of the loop is smoothly curved at the base portion of the loop and has no recess into the stranded wires. The absence of the recess makes loosening less likely when attached to a mating material. Since the entire circumference of the loop is not melted, the loop can be formed using a small welding current.

Description

terminal wire

[0001] The present invention relates to a terminalized electric wire in which the tip of a stranded wire of copper or the like is processed into a loop shape so that it can be used as a terminal.

[0002] It is known to process the tip of a stranded wire into a loop and then fuse the loop by welding to form a loop-shaped terminal (see, for example, Patent Document 1: JP 2012-209017A and Patent Document 2: JP 2016-177999A). An electric wire having a loop formed by welding a stranded wire to its tip is called a terminalized electric wire.

[0003] FIG. 7 shows a conventional terminated electric wire 2, with 4 representing the loop, 6 representing the hole in the loop 4, and 8 representing the stranded wire. In a terminated electric wire, a triangular recess 7 generally occurs at the base of the loop 4. The recess 7 occurs when the stranded wire 8 changes direction at the base of the loop 4, and can cause loosening when the terminated electric wire 2 is attached to a mating part. For example, after the terminated electric wire is attached to a bolt with a circular cross section, the triangular recess remains as a gap between the bolt and the inner surface of the loop, causing loosening due to machine vibration or impact. Patent Documents 1 and 2 describe the occurrence of a recess at the base of the loop, but do not describe a method for eliminating the recess.

[0004] Furthermore, in the process of melting and solidifying the loop portion as in Patent Document 1, undulations may occur along the circumference of the loop. The undulations may result in insufficient adhesion and fastening to the mating material, which may also cause loosening.

[0005] Patent Publication No. 2012-209017A Patent Publication No. 2016-177999A

[0006] The object of the present invention is to prevent the occurrence of a depression at the base of the loop of a terminalized electric wire, to ensure sufficient adhesion and fastening to the mating material, and to eliminate loosening during or after installation.

[0007] This invention is a terminalized electric wire consisting of a loop at the tip and a stranded wire extending from the base of the loop, in which at the fusion part at the base of the loop, the two stranded wires cross and the stranded wires melt, and the stranded wires that make up the stranded wire are welded together and integrated, and from both sides of the base of the loop to the tip of the loop, the stranded wires maintain their shape while the stranded wires are diffusion-bonded to each other, and further, the inner surface of the loop is smoothly curved at the base of the loop, with no recessed part toward the stranded wire side.

[0008] Preferably, in the portion from the tip of the loop to just before the diffusion bonded portion, the strands of the stranded wire are independent of each other and are not bonded together.

[0009] Preferably, the portion of the loop from the tip to just before the diffusion-bonded portion forms a deformed portion in which the stranded wire is compressed and deformed flat. The provision of the deformed portion reduces the height difference along the circumference of the loop, making it easier to fix to the mating material. Furthermore, when the loop is formed by resistance welding, the shape of the loop is kept constant, making it easier to prevent the occurrence of indentations.

[0010] Preferably, one of the upper and lower surfaces of the loop is flat, and the other of the upper and lower surfaces has three levels of height, from high to low: the deformed portion, the diffusion-bonded portion, and the fused portion. Since one of the upper and lower surfaces of the loop is flat, it is easy to attach the terminalized electric wire to the mating material. The loop is formed by resistance welding, with the current density being maximized in the fused portion, intermediate in the diffusion-bonded portion, and minimal or zero in the deformed portion. The fused portion, intermediate portion, and deformed portion can be formed by changing the density of the welding current.

[0011] Preferably, there are two stranded wires at the base of the loop, with one stranded wire extending from the base of the loop and the other stranded wire terminating at the base of the loop. Since the loop is the main part that requires electrical conductivity and mechanical strength in a terminalized electric wire, having only one stranded wire extending from the base of the loop allows the terminalized electric wire to be made lighter, smaller in diameter, and less expensive.

[0012] Preferably, the loop is provided on both ends of the stranded wire. The terminalized electric wire can connect two mating members.

[0013] In this invention, there is no indentation on the inner circumference of the base of the loop, so the terminalized electric wire is less likely to loosen when attached to the mating material. This is because the two stranded wires are crossed at the base of the loop and welded in a shape without an indentation, fixing the shape of the loop. In addition, the molten wires try to fill the indentation, which also contributes to eliminating the indentation.

[0014] Furthermore, in this invention, the diffusion-bonded portions 20a, 20b and the deformed portion 22 of the loop 14 have a compression allowance, which deforms during attachment to the mating material, filling gaps and preventing loosening after attachment. For example, the loop portion of the terminalized electric wire in Patent Document 1 is melted and solidified. In contrast, in the loop 14 of the present invention, the stranded wire maintains its shape as a bare wire at the diffusion-bonded portion, etc., resulting in the aforementioned compression allowance. The compression allowance deforms to follow the shape of the mating material, closely adhering to the mating material and enabling fastening to the mating material, thereby reducing gaps during attachment and loosening after attachment. As a result, the terminalized electric wires 10, 12 of the present invention can carry large currents.

[0015] Furthermore, in this invention, the stranded wire is melted only at the base of the loop, rather than melting the entire loop, so the loop can be formed with a small welding current. If the entire loop, which crosses the stranded wire, is melted, the base, where the welding current density is likely to be high, is prone to overheating and breakage, but in this invention, breakage of the base is less likely to occur.

[0016] The applications of the present invention are not particularly limited, but the terminalized electric wire of the present invention can be used as a component for conducting electrical connections in narrow and complex devices, as a substitute for bus bars for conducting electrical connections in electric vehicles, hybrid vehicles, etc. Furthermore, the flexibility of the stranded wire can be utilized for conducting electrical connections in mechanical devices including moving parts, such as robots. In addition, the wire can be used for conducting electrical connections in any other mechanical devices.

[0017] FIG. 1 is a plan view of a main part of a terminalized electric wire according to an embodiment; FIG. 2 is a bottom view of a main part of a terminalized electric wire according to an embodiment; FIG. 3 is a plan view of a main part of a terminalized electric wire according to a modified example; FIG. 4 is a plan view of a terminalized electric wire according to a modified example;

[0018] The best mode for carrying out the present invention will be described below. The present invention is not limited to the mode, but is defined by the claims, and can be modified by adding matters known to those skilled in the art to the mode.

[0019] 1 to 6 show an embodiment and its modifications. In Fig. 1 and Fig. 2, the terminalized electric wire 10 is composed of a pair of twisted wires 8, 9 made of copper or the like, and has loops 14 (portions that act as terminals) at both ends, for example, but the loop 14 may be provided at only one end. The twisted wires 8, 9 are formed by twisting together multiple wires, and the twisted wires 8, 9 before the loop 14 is formed are a single twisted wire. The twisted wires make one turn around the approximately circular loop 14, and the loop 14 has, for example, a circular hole 16 in its center. The side of the loop 14 facing the twisted wires 8, 9 is called the base, and the opposite side (the left side in Figs. 1 and 2) is called the tip.

[0020] 1, the loop 14 has a fusion zone 18 at its base, which is the shortest and thinnest, and diffusion-bonded zones 20a and 20b on either side of it along the circumferential direction of the loop 14. The tip side of the loop 14 is occupied by a deformed zone 22, which is the tallest and has a thickness greater than that of the fusion zone 18 and the diffusion-bonded zones 20a and 20b.

[0021] As shown in Figure 2, when viewed from below, the bottom surface of the loop 14 is almost flat, with a fusion zone 18 at the base, diffusion-bonded zones 20a and 20b on either side, and a deformed zone 22 at the tip. The area of ​​the fusion zone 18 is larger in Figure 2 than in Figure 1, and conversely, the area of ​​the diffusion-bonded zones 20a and 20b is smaller in Figure 2 than in Figure 1. The area of ​​the deformed zone 22 is not significantly different between Figures 1 and 2.

[0022] Before welding, the stranded wires cross once at fusion zone 18 at the base of loop 14, overlapping one another, with diffusion fusion zone 20a connecting to stranded wire 9 and diffusion fusion zone 20b connecting to stranded wire 8. The upper and lower stranded wires are then fused together by resistance welding to form fusion zone 18.

[0023] 1 and 2, a pair of twisted wires 8, 9 extend from the base of the loop 14 in the opposite direction to the loop 14. However, one of the twisted wires 8, 9 may be cut at the position of the cutting portion 24 shown by the chain line in Figures 1 and 2 to form the terminated electric wire 12 shown in Figure 3. The terminated electric wire 12 in Figure 3 is similar to the terminated electric wire 10 in Figures 1 and 2, except that the twisted wire 9 is cut at the cutting portion 24.

[0024] As shown in Figure 4, the terminalized electric wire 12 has loops 14, 14 at both ends, for example, and the middle of the loops 14, 14 is covered with, for example, a plastic coating 26. The terminalized electric wires 10, 12 are capable of carrying large currents and have high mechanical strength and attachment strength to the mating material. Since the loop 14 and its surroundings are what require high conductivity and mechanical strength in the terminalized electric wires 10, 12, it is reasonable to configure the middle portion with only one stranded wire 8, as shown in Figure 4. The terminalized electric wires 10, 12 can be used for any purpose, but are used, for example, as a bus bar for connecting a generator, motor, etc. to a battery in an electrically powered vehicle such as an electric vehicle or hybrid vehicle, for electrical connections around the battery.

[0025] FIG. 5 shows the manufacturing process for terminalized electric wires 10, 12. The stranded wires 8, 9 are wound, for example, one turn around a pin 32 extending upright from a die 30 to form a loop, and the stranded wires 8, 9 are then pulled in the direction of the arrow in the figure to fasten the pin 32 with the stranded wires 8, 9. If the stranded wires 8, 9 are resistance-welded while maintaining the loop shape, no indentations are formed. For example, while the loop is held in the die 30, a movable die (not shown) is lowered from above to crush the loop and fix the loop shape. Next, for example, the loop is held in the die 30, and a movable upper electrode 40 is lowered using the die 30 as the lower electrode to form the loop 14 by resistance welding.

[0026] 5 and 6, the bottom of the upper electrode 40 has an advancing portion 44, a receding portion 42, and an intermediate portion 46, with the advancing portion 44 advancing downward, the receding portion 42 receding upward relative to the advancing portion 44, and the intermediate portion 46 being located between them. The advancing portion 44 corresponds to the fusion zone 18, the intermediate portion 46 corresponds to the diffusion-bonded portions 20a and 20b, and the receding portion 42 corresponds to the deformation portion 22.

[0027] When welding current is applied from the state shown in Figure 6, the maximum current density is obtained at the advancing portion 44, the current density is low at the intermediate portions 46 on both sides, and the current density is lowest at the retreating portion 42. As a result, the stranded wire melts at the fusion zone 18, and when the cross section of the fusion zone is observed, no individual strands are visible. As the position changes from top to bottom in Figure 6, the welding current spreads horizontally. Therefore, as shown in Figures 1 and 2, the fusion zone 18 in Figure 2 is wider than in Figure 1. The welding current from the intermediate portion 46 does not generate enough heat to melt the strands, but it does diffusion-bond the strands to each other and secure them together. When the diffusion-bonded portion 20b was cut and the cross section was observed, the individual strands were visible, but the strands were still firmly bonded to each other. Furthermore, when the diffusion-bonded portion 20b was cut from the loop 14, the diffusion-bonded portion 20b maintained a consistent shape.

[0028] The deformed portion 22 is formed by the flattening of the stranded wire by pressing and by the pressure applied by the upper electrode during resistance welding. Although the stranded wire is compressed in the deformed portion 22, the strands are independent and not bonded to each other due to the low density of the welding current. For example, when the deformed portion 22 is cut out from the loop 14, the deformed portion 22 separates into strands. The purpose of providing the deformed portion 22 is to maintain a consistent loop shape during welding by pressing and to reduce the height difference at the bottom of the upper electrode 40. The provision of the deformed portion also serves to reduce the height difference around the loop 14, making it easier to attach to the mating material. A large height difference around the loop 14 makes it difficult to tighten when attaching to the mating material. The change in thickness of the loop portion described above is smaller than the height difference referred to here and does not affect attachment to the mating material.

[0029] Furthermore, the loop portion has a compression allowance due to the state of the wire at the diffusion-bonded portions 20a, 20b and the deformed portion 22. The compression allowance of the loop portion enables close contact and fastening that follows the shape of the mating material when attached to the mating material, preventing loosening after attachment and allowing a large current to flow.

[0030] By eliminating the gap between the pin 32 and the stranded wire when winding the stranded wires 8 and 9 around the pin 32, no indentations occur in the loop 14. In addition, the melted portion 18 melts, and if an indentation occurs, the melted copper fills it, which also helps to eliminate the indentation. Because there is no indentation, the terminalized electric wires 10 and 12 can be attached to a mating material as a conductive connection member, such as a bus bar.

[0031] Instead of melting the entire periphery of the loop 14, only the fusion zone 18 at the base is melted, thereby reducing the welding current and facilitating welding. Furthermore, by providing diffusion-bonded sections 20a, 20b on both sides of the fusion zone 18, the structure of the loop 14 gradually changes from the fusion zone to a collection of independent wires, thereby increasing the strength of the loop 14. Furthermore, the bottom surface (the surface in Figure 2) of the loop 14 is nearly flat, making it easy to attach to a mating material. The terminalized electric wire 12 in Figure 4 has only one stranded wire in the middle section, making it lightweight, small-diameter, inexpensive, and efficient.

[0032] The method for manufacturing the terminalized electric wires 10, 12 is arbitrary. For example, after pressing as shown in FIG. 5, the loop may be transferred to another lower electrode and welded. Alternatively, the bottom surface of the upper electrode may be flat, and an extension portion and an intermediate portion may be provided on the upper surface of the lower electrode. The cut portion 24 may be provided after pressing and before welding, or after welding. Although the loop 14 is circular in this embodiment, it may also be rectangular or other shapes.

[0033] 2 Terminalized electric wire 4 Loop 6 Hole 7 Indentation portion 8, 9 Stranded wire 10, 12 Terminalized electric wire 14 Loop 16 Hole 18 Melted portion 20a, 20b Diffusion bonded portion 22 Deformed portion 24 Cut portion 26 Coating 30 Die (lower electrode) 32 Pin 40 Upper electrode 42 Retracted portion 44 Protruding portion 46 Intermediate portion

Claims

1. A terminalized electric wire consisting of a loop at the tip and a stranded wire extending from the base of the loop, wherein at the fusion part at the base of the loop, the two stranded wires cross and the stranded wires are fused, and the stranded wires that make up the stranded wire are fixed together and integrated; from both sides of the base of the loop to the tip of the loop, the stranded wires maintain their shape and the stranded wires are diffusion-bonded together; and further, the inner surface of the loop is smoothly curved at the base of the loop, with no recessed part toward the stranded wire side.

2. The terminalized electric wire of claim 1, wherein the stranded wires are independent of each other and not joined in the section from the tip of the loop to just before the diffusion-bonded section.

3. The terminalized electric wire of claim 2, wherein the portion from the tip of the loop to just before the diffusion bonded portion forms a deformed portion in which the stranded wire is compressed and deformed flat.

4. A terminalized electric wire according to claim 3, characterized in that one of the upper and lower surfaces of the loop is flat, and the other upper and lower surface has three levels of height, from high to low, namely, a deformed portion, a diffusion-bonded portion, and a fused portion.

5. A terminalized electric wire according to any one of claims 1 to 4, characterized in that there are two twisted wires at the base of the loop, one twisted wire extending from the base of the loop and the other twisted wire terminating at the base of the loop.

6. A terminalized electric wire according to any one of claims 1 to 4, characterized in that the loop is provided on both ends of the stranded wire.

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