JP7732773B2 - Electric wire with terminal, wire harness, and method for manufacturing electric wire with terminal using terminal crimping blade - Google Patents

Description

The present invention relates to terminal-attached electric wires, etc., used in automobiles, etc.

Automotive wiring harnesses typically involve connecting crimp terminals to the conductors of covered conductors, bundling them together, and then routing them as signal wires in automobiles and other applications. A typical covered conductor and crimp terminal are connected by removing the covering from the tip of the covered conductor, crimping the exposed conductor to the conductor crimping portion, and then crimping the covering at the covering crimping portion. Automotive wiring harnesses meet the connection strength requirements between the crimp terminal and covered conductor by combining the connection strength of the conductor crimping portion and the connection strength of the covering crimping portion.

As the electric wires used become thinner, it becomes difficult to maintain strength using only the conductor that constitutes the wire, and so electric wires containing reinforcing members are being considered. For example, when using an electric wire made of a conductor with a tensile strength of around 30 N, in order to ensure the tensile strength exceeding 80 N required for electric wires for automobiles, an electric wire containing a reinforcing member has been proposed in which the conductor is wound spirally around the outer periphery of a metallic or non-metallic reinforcing member. One method for manufacturing such electric wires is to strip the conductor in a step, expose the reinforcing member, insert it into a sleeve, crimp the reinforcing member with a steel clamp, and then integrate it with a curable resin such as an adhesive, while the conductor portion is crimped with an aluminum clamp or other material (Patent Documents 1 and 2).

Japanese Utility Model Application Laid-Open Publication No. 61-046827 Japanese Patent Application Publication No. 8-237839

In recent years, particularly in the automotive field, the number of ECUs and sensors has increased in response to CASE and other issues, resulting in a significant increase in the number of electric wires used. In this context, increasing the wire diameter of wire harnesses has become an issue. Therefore, there is a demand for even smaller diameter electric wires for automobiles. For example, there is a demand for electric wires with a diameter of 0.35 sq (sq: ^mm2 ) or less, which is the conventional general diameter.

The conductor crimping portion must satisfy both the connection strength between the wire and terminal and the electrical connection resistance between the conductor and terminal. In order to meet the required specifications for both the connection strength with the wire and the electrical connection resistance with the conductor, the compression ratio of the conductor crimping portion must be appropriately set. However, as the wire diameter becomes thinner, it becomes difficult to satisfy both requirements at the same compression ratio.

For example, when connecting a large-diameter covered conductor to a crimp terminal using conventional technology, it is possible to crimp the conductor at the crimping portion with a compression ratio that achieves both connection strength and connection resistance. However, as the diameter of the wire becomes smaller, the range of appropriate crimping conditions for both connection strength and electrical resistance becomes narrower. This is because attempting to ensure connection strength results in the conductor breaking and increasing connection resistance, while prioritizing connection resistance results in insufficient connection strength, which can lead to the wire coming loose. In this way, the smaller the wire diameter, the more difficult it becomes to achieve both connection strength and electrical resistance.

Furthermore, connecting conventional wires with reinforced tensile members requires separate crimping processes for crimping the tensile member and the conductor. This increases the number of parts and the number of man-hours required, resulting in high costs. The step-stripping process itself becomes particularly difficult as the wire diameter becomes smaller. As such, conventional methods have the problem of complicated manufacturing processes, which increase processing costs.

The present invention was made in consideration of these problems, and aims to provide a terminal-attached electric wire or the like that is easy to crimp and can achieve both connection strength and connection resistance.

In order to achieve the above-mentioned object, a first invention is an electric wire with terminal in which a covered conductor wire and a terminal are electrically connected, the terminal comprising: a conductor crimping portion to which the conductor wire exposed from the coating at the tip of the covered conductor wire is crimped; and a coating crimping portion to which the coating of the covered conductor wire is crimped, at least a portion of the conductor crimping portion has a tubular shape that is closed in the circumferential direction, an electric wire holding portion is provided at the tip side of the conductor crimping portion, and a conductive portion is formed at the rear end side of the conductor crimping portion for achieving conductivity with the conductor wire, the electric wire holding portion and the conductive portion have different compressibility, the covered conductor wire has a plurality of the conductor wires and at least one strength member, the wire holding portion holds both the conductor wire, at least a portion of which is broken, and the strength member, and the conductor wire is not broken in the conductive portion, and the electrical resistance of the conductor wire at the conductive portion is lower than the electrical resistance of the conductor wire at the electric wire holding portion.

The inner surface of the conductor crimping portion may be provided with projections and recesses.
The strength member may also include fibers, and some of the fibers of the strength member may enter the gaps in the broken conductor.

It is desirable that the compressibility of the electric wire holding portion be smaller than that of the conductive portion.

In a cross section perpendicular to the longitudinal direction of the covered conductor, the strength member may be located approximately at the center of the covered conductor, and the conductor may be arranged on the outer periphery of the strength member. Furthermore, the conductor may be twisted in the longitudinal direction of the covered conductor.

At least the tip of the conductor may be compressed from the outer periphery, or the conductor may be plated all at once from the outer periphery.

The compression rate of the coating crimping portion may be smaller than the compression rate of the conductive portion.

According to the first invention, by dividing the conductor crimping portion into two functional parts - a wire holding portion that holds the conductor to increase connection strength, and a conductive portion that ensures continuity with the conductor to reduce connection resistance - it is possible to satisfy both connection strength and connection resistance. In this case, the conductor crimping portion can be crimped using the same method as conventional methods, making the process easy.

In particular, since at least a portion of the conductor crimping portion is tubular, the conductor can be reliably crimped from the entire circumference, thereby suppressing local stress (deformation) on the conductor during crimping.
Furthermore, by including a plurality of the conductor wires and at least one tension member in the coated conductor wire, the tension member can ensure the tensile strength of the conductor wires. In this case, if both the conductor wires and the tension member are held by the wire holding portion, high connection strength can be ensured. Furthermore, since there is no need to connect the tension member and the conductor wire with separate clamps as in the conventional method, the number of parts required is reduced and the connection work is easy.
Furthermore, in the wire holding portion, a part of the tensile strength member or the like enters the gap of the broken conductor, thereby increasing the pull-out resistance of the conductor and ensuring connection strength. Meanwhile, electrical continuity between the conductor and the crimp terminal is ensured by the conductive portion.

In addition, in this case, by making the compression rate of the wire holding portion smaller than that of the conductive portion, i.e., by strongly compressing the wire holding portion, the connection strength between the terminal and the covered conductor can be more reliably ensured.

Furthermore, if the conductor is positioned around the outer periphery of the central tension member in a cross section perpendicular to the longitudinal direction of the covered conductor, the conductor can be reliably crimped. In this case, the conductor may be twisted around the outer periphery of the tension member in the longitudinal direction.

In addition, by forming a terminal processing section, such as by compressing the tip of the conductor from the outer periphery or by plating the entire conductor from the outer periphery, it is possible to prevent the conductor from coming apart when the tip of the conductor is inserted into the tubular conductor crimping section.

In addition, by making the compression rate of the coating crimping portion smaller than that of the conductive portion, the coating portion can be securely held in place.

The second invention is a wire harness characterized by integrating multiple terminal-equipped electric wires, including the terminal-equipped electric wire of the first invention.

According to the second invention, a wire harness can be obtained in which multiple thin-diameter electric wires are bundled together.

A third invention is a method for manufacturing an electric wire with a terminal using a terminal crimping blade die, wherein the electric wire with terminal is configured such that a covered conductor wire and a terminal are electrically connected to each other, and the terminal comprises a conductor crimping portion to which the conductor wire exposed from the coating at the tip of the covered conductor wire is crimped, and a coating crimping portion to which the coating of the covered conductor wire is crimped, at least a part of the conductor crimping portion has a tubular shape closed in the circumferential direction, a wire holding portion is provided at the tip side of the conductor crimping portion, and a conductive portion for obtaining conductivity with the conductor wire is formed at the rear end side of the conductor crimping portion, the wire holding portion and the conductive portion have different compressibility, the covered conductor wire has a plurality of the conductor wires and at least one strength member, and the terminal crimping blade die comprises an upper blade die and a lower blade die, and the upper blade die and the lower blade die are configured such that ... the upper blade type and the lower blade type at a portion corresponding to the wire holding portion are formed so as to have a substantially circular cross section when the upper blade type and the lower blade type are joined together, and the spacing between the upper blade type and the lower blade type at a portion corresponding to the wire holding portion is formed narrower than the spacing between the upper blade type and the lower blade type at a portion corresponding to the conductive portion, and the method for manufacturing an electric wire with a terminal includes a step of engaging the upper blade type and the lower blade type of the terminal crimping blade to crimp the conductor crimping portion and the insulation crimping portion, wherein in the crimping step, at least a portion of the conductor wire is broken to hold both the conductor wire and the strength member at a portion corresponding to the wire holding portion provided on the front end side of the conductor crimping portion, and at a portion corresponding to the conductive portion formed on the rear end side of the conductor crimping portion, the conductor wire is not broken and conductivity is ensured, and the electrical resistance of the conductor wire at the conductive portion is lower than the electrical resistance of the conductor wire at the wire holding portion .

According to the third aspect of the present invention, the electric wire with terminal of the first aspect of the present invention can be manufactured.

The present invention makes it possible to provide terminal-attached electric wires and the like that are easy to crimp and that achieve both low connection strength and low connection resistance.

FIG. 2 is a perspective view showing the electric wire with terminal 10. FIG. 2 is a cross-sectional view showing the terminal-attached electric wire 10. 4A to 4C are cross-sectional views of the electric wire holding portion 7a. FIG. 2 is a diagram showing the terminal 1 and the coated conductor wire 11 before crimping. 1A is a diagram showing the tip of the conductor 13, FIG. 1B is a diagram showing the tip of the conductor 13 before terminal processing, and FIG. 1C and FIG. 1D are diagrams showing the shape of the terminal processing portion 19. FIG. 10A and 10B are diagrams showing other forms of the terminal processing unit 19. FIG. 4A and 4B are diagrams showing the crimping process of the crimping portion 5. FIG. FIG. 2 is a diagram showing a terminal 1a and a coated conductor wire 11 before crimping. FIG. 2 is a diagram showing the terminal 1b and the coated conductor wire 11 before crimping. FIG. 2 is a diagram showing the terminal 1c and the coated conductor wire 11 before crimping. FIG. 2 is a diagram showing a terminal 1d and a coated conductor wire 11 before crimping. FIG. 2 is a diagram showing a terminal 1e and a coated conductor wire 11 before crimping. FIG. 10A and 10B are diagrams showing cross sections of other coated conductor wires 11. FIG.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an electric wire with terminal 10, and Fig. 2 is a cross-sectional view of the electric wire with terminal 10. The electric wire with terminal 10 is configured by electrically connecting a terminal 1 and a coated conductor wire 11.

The coated conductor wire 11 consists of a conductor wire 13 made of, for example, copper, copper alloy, aluminum, or aluminum alloy, and a coating portion 15 that covers the conductor wire 13. In other words, the coated conductor wire 11 comprises the coating portion 15 and the conductor wire 13 exposed from its tip.

The terminal 1 is made of, for example, copper, copper alloy, aluminum, or aluminum alloy. A coated conductor wire 11 is connected to the terminal 1. The terminal 1 is composed of a terminal body 3 and a crimping portion 5 connected via a transition portion 4.

The terminal body 3 is formed by forming a plate material of a predetermined shape into a cylindrical body with a rectangular cross section. The terminal body 3 has an internal resilient contact piece formed by folding the plate material into the rectangular cylindrical body. A male terminal or the like is inserted into the front end of the terminal body 3 to connect it. Note that the following explanation shows an example in which the terminal body 3 is a female terminal that allows the insertion of an insertion tab (not shown) of a male terminal or the like, but the detailed shape of this terminal body 3 is not particularly limited in the present invention. For example, the female terminal body 3 may be replaced with an insertion tab of a male terminal, or a bolt fastening portion like a round terminal may be provided.

The crimping portion 5 of the terminal 1 is the portion that is crimped to the insulated conductor wire 11, and includes a conductor crimping portion 7 that crimps the conductor wire 13 exposed from the insulated portion 15 at the tip of the insulated conductor wire 11, and a coating crimping portion 9 that crimps the insulated portion 15 of the insulated conductor wire 11. That is, the conductor wire 13 exposed when the insulated portion 15 is stripped is crimped by the conductor crimping portion 7, electrically connecting the conductor wire 13 to the terminal 1. The insulated portion 15 of the insulated conductor wire 11 is also crimped by the coating crimping portion 9 of the terminal 1. In this embodiment, the conductor crimping portion 7 and the coating crimping portion 9 are integrally configured to have a tubular (approximately cylindrical) shape that is closed in the circumferential direction.

In addition, serrations (not shown) may be provided in the width direction (direction perpendicular to the longitudinal direction) on part of the inner surface of the conductor crimping portion 7. By forming serrations in this manner, the oxide film on the surface of the conductor 13 can be easily destroyed when the conductor 13 is crimped, and the contact area with the conductor 13 can be increased.

The wire crimping portion 7 has a wire holding portion 7a at the tip end (closer to the terminal body 3) that has a relatively strong holding force for the wire 13. Additionally, a conductive portion 7b is formed at the rear end (closer to the insulation crimping portion 9) of the wire crimping portion 7 to establish electrical continuity with the wire 13. In other words, the wire crimping portion 7 has a wire holding portion 7a and a conductive portion 7b.

The tensile strength (connection strength) of the conductor 13 in the wire holding portion 7a is greater than the tensile strength (connection strength) of the conductor 13 in the conductive portion 7b. For example, the compression ratio (cross-sectional area of the conductor 13 after compression/cross-sectional area of the conductor 13 before compression) in the wire holding portion 7a is smaller than that in the conductive portion 7b. In other words, the amount of compression in the wire holding portion 7a is greater than the amount of compression in the conductive portion 7b, and the wire holding portion 7a is strongly crimped.

In this way, because the wire holding portion 7a is strongly crimped, at least a portion of the conductor 13 may be broken. Breaking a portion of the conductor 13 increases electrical resistance, but some of the fibers of the tensile member 17 enter the gaps in the broken conductor 13, increasing the pull-out resistance of the conductor 13 and ensuring connection strength. On the other hand, in the conductive portion 7b, the conductor 13 is not broken in order to keep electrical resistance low.

The compression rate of the coating crimping portion 9 (cross-sectional area of the coating 15 after compression/cross-sectional area of the coating 15 before compression) may be smaller than the compression rate of the conductive portion 7b. In other words, the compression amount of the coating crimping portion 9 may be larger than the compression amount of the conductive portion 7b. Even in this case, the thickness of the coating 15 causes the outer diameter of the coating crimping portion 9 to be larger than the outer diameter of the conductive portion 7b.

Figure 3(a) is a diagram showing a cross section of the wire holding portion 7a. In the example shown in Figure 3(a), the conductor wire 13 consists of seven strands. In the wire holding portion 7a, the conductor wire 13 is compressed and crimped into a substantially circular shape. Note that the shape of the wire holding portion 7a after crimping does not necessarily have to be substantially circular, but it is desirable that the cross section of the conductive portion 7b after crimping be substantially circular.

The number of wires in the conductor 13 is not particularly limited. For example, as shown in Figure 3(b), there may be 16 wires. It is preferable that the wires are twisted together.

The covered conductor wire 11 may also have at least one conductor wire 13 and a strength member coated with a coating 15. The strength member is a member that receives tension when a tensile load is applied. For example, as shown in FIG. 3(c), in a cross section perpendicular to the longitudinal direction of the covered conductor wire 11, at least one strength member 17 may be located approximately at the center of the covered conductor wire 11, and multiple conductor wires 13 may be arranged around the strength member 17. In this case, each conductor wire 13 (strand) arranged around the strength member 17 may have the same cross-sectional area and shape. Furthermore, the conductor wire 13 may be twisted spirally around the strength member 17 in the longitudinal direction of the covered conductor wire 11. In this case, both the conductor wire 13 and the strength member 17 are crimped and held by the wire holding portion 7a and the conductive portion 7b.

The arrangement of the strength members 17 is not limited to the example shown in Figure 3(c). For example, the conductor wire 13 and the strength members 17 may be arranged so as to be twisted together. Alternatively, multiple conductor wires 13, each having a strength member 17 coated with a conductor, may be twisted together. Alternatively, the conductor may be arranged so as to cover the outer periphery of the central strength member 17. In other words, in the case of a coated conductor wire 11 containing a strength member, there are no particular restrictions on its cross-sectional shape as long as it has at least one conductor wire and at least one strength member. The strength member 17 may be a single (integral) strength wire, or may be made up of multiple strands.

Here, it is desirable that the cross-sectional area of the conductor 13 (total cross-sectional area of the wires) be 0.3 sq or less, and in this case, it is desirable that the terminal 1 be capable of crimping a conductor 13 with a cross-sectional area of 0.3 sq or less. Furthermore ... for example, when the conductor 13 is used together with a tensile strength member 17, the cross-sectional area of the conductor 13 may be 0.05 sq or less. The smaller the cross-sectional area of the conductor 13, the greater the effect of this embodiment.

The tension member 17 may be a metal wire such as a steel wire, or may be made of resin or fiber-reinforced resin. As mentioned above, the tension member 17 may be a single wire or a bundle of multiple fibers such as aramid fiber. By using such a tension member 17, it is possible to ensure a tensile strength of 50 N or more for the conductor 13 in the wire holding portion 7a, even if the cross-sectional area of the conductor 13 is 0.05 sq. or less.

Next, a method for manufacturing the electric wire with terminal 10 will be described. Figure 4 is a perspective view showing the terminal 1 and the covered conductor wire 11 before crimping. As described above, the terminal 1 has a terminal body 3 and a crimping portion 5. The crimping portion 5 is configured as a roughly cylindrical integral part of the conductor crimping portion 7 and the covering crimping portion 9. The crimping portion 5 may be formed, for example, by rolling a plate member, butting the ends together, and joining them by welding in the longitudinal direction, or by expanding a tubular member to form the terminal 1. The conductor crimping portion 7 and the covering crimping portion 9 may have the same diameter, or, as shown in the figure, the inner diameter of the conductor crimping portion 7 may be roughly constant and the inner diameter of the covering crimping portion 9 may be larger than the inner diameter of the conductor crimping portion 7.

First, as described above, the coating 15 at the tip of the coated conductor wire 11 is stripped to expose the conductor wire 13 at the tip. Next, as shown in Figure 5(a), a terminal processing section 19 may be formed at the tip of the conductor wire 13 before insertion into the crimping section 5 of the terminal 1. The terminal processing section 19 is a processing section that integrates the individual wires of the conductor wire 13 to prevent them from coming apart.

Figure 5(b) shows the shape of the tip of the conductor 13 before terminal processing. In this embodiment, when viewed from the tip of the coated conductor 11, the tension member 17 is located approximately in the center, with the conductor 13 located around it. The conductor 13 is made up of multiple strands. Note that this embodiment describes a case where the tension member 17 is located in the center, but the same applies to other coated conductors.

In such cases, as shown in Figure 5(c), the terminal processing portion 19 can be formed by compressing at least the tip of the conductor 13 from the outer periphery. In this way, compressing the tip of the conductor 13 from the outer periphery prevents the wire from unraveling, making it easier to insert the wire into the tubular crimping portion 5.

Alternatively, as shown in Figure 5(d), at least the tip of the conductor 13 may be plated all at once to form the terminal processing portion 19 with a plating layer 21. In this way, plating the tip of the conductor 13 all at once from the outer periphery prevents the wire from coming apart, making it easier to insert into the tubular crimping portion 5.

Note that when plating the conductor wires 13 en bloc from the outer periphery, the temperature may become very high depending on the plating method. If plating is performed en bloc after twisting the conductor wires 13 using this plating method, the tensile strength of the reinforcing members 17 may be deteriorated by the heat, resulting in a decrease in tensile strength.

In such cases, as shown in Figure 6(a), a plating layer 21 may be formed on each conductor before twisting them around the outer periphery of the tension member 17. Alternatively, as shown in Figure 6(b), a plating layer 21 may be formed on each conductor, and then the tips of multiple conductors may be plated together starting from the outer periphery. In this case, the type of plating for each conductor may be different from the type of plating performed on all conductors at once. Plating all at once can prevent the conductors from coming apart, but bundling and plating all conductors at once can result in areas with thick or thin plating due to factors such as the shape of the conductors. In contrast, performing a primer plating process on each conductor in advance can reduce this effect, enabling approximately uniform plating all at once.

The terminal processing section 19 is not limited to methods using compression or plating; for example, the tip of the conductor 13 may be soldered or welded to prevent the wires from coming apart. It is also possible to combine multiple terminal processing methods, such as compression from the periphery and batch plating.

Next, the coated conductor wire 11, whose tip has been treated in this manner, is inserted into the rear end of the tubular crimping portion 5 of the terminal 1. When the tip of the coated conductor wire 11 is inserted into the crimping portion 5, the exposed portion of the conductor wire 13 is located inside the conductor crimping portion 7, and the coating portion 15 is located inside the coating crimping portion 9. At this time, the tip of the conductor wire 13 may protrude from the tip of the conductor crimping portion 7.

Figure 7(a) is a cross-sectional view showing the upper blade die 31a, lower blade die 31b, etc., before crimping the terminal crimping blade for manufacturing a terminal-attached electric wire 10, and Figure 7(b) is a cross-sectional view showing the crimping portion 5 during crimping. The upper blade die 31a and lower blade die 31b have a roughly semi-cylindrical cavity extending in the longitudinal direction. The upper blade die 31a also includes a coating crimping blade die 34 that corresponds to the coating crimping portion 9 and has a diameter slightly smaller than the radius of the coating crimping portion 9, and conductor crimping blade dies 32a, 32b that correspond to the conductor crimping portion 7 and have a smaller diameter than the coating crimping blade die 34. In other words, the upper blade die 31a and lower blade die 31b are formed so that both the portions corresponding to the conductor crimping portion 7 and the coating crimping portion 9 have a roughly circular cross section when the terminal 1 is crimped.

The conductor wire crimping blade die 32a is a blade die that corresponds to the wire holding portion 7a, and the conductor wire crimping blade die 32b is a blade die that corresponds to the conductive portion 7b. In other words, the diameter of the conductor wire crimping blade die 32a is smaller than the diameter of the conductor wire crimping blade die 32b, and the distance between the upper blade die 31a and the lower blade die 31b in the portion that corresponds to the wire holding portion 7a is narrower than the distance between the upper blade die 31a and the lower blade die 31b in the portion that corresponds to the conductive portion 7b.

The conductive portion 7b may be relatively longer than the wire holding portion 7a to ensure conductivity between the coated conductor wire 11 and the terminal 1. On the other hand, even if the wire holding portion 7a is short, the strength of the two will be sufficiently high as long as the conductor wire 13 or the tensile strength member 17 and the terminal 1 are securely attached with appropriate pressure, so the wire holding portion 7a may be relatively shorter than the conductive portion 7b.

As shown in Figure 7(b), when the upper blade die 31a and lower blade die 31b are engaged and the crimping portion 5 is compressed, the conductor crimping portion 7 is crimped to the conductor wire 13, and the insulation crimping portion 9 is crimped to the insulation portion 15. At this time, the wire holding portion 7a has the smallest diameter, followed by the conductive portion 7b, and the insulation crimping portion 9 has the largest diameter. In this way, the terminal-attached electric wire 10 can be obtained. Furthermore, a wire harness can be obtained in which multiple terminal-attached electric wires, including the obtained terminal-attached electric wire 10, are integrated.

As mentioned above, the compression rate of the wire holding portion 7a is smaller than that of the conductive portion 7b, and the compression rate of the insulation crimping portion 9 is smaller than that of the conductive portion 7b. Here, if the cross-sectional area of the insulation 15 before the crimping process (the total cross-sectional area inside the outer circumferential surface of the insulation crimping portion 9) is A0, and the internal cross-sectional area of the insulation crimping portion 9 after being compressed by the upper blade die 31a and lower blade die 31b is A2, then the compression rate of the insulation crimping portion 9 = A2/A0 (%).

Similarly, if the cross-sectional area of the conductor 13 before the crimping process (if a tensile strength member is included, the total cross-sectional area of the conductor 13 including the tensile strength member) is A1, and the internal cross-sectional areas of the conductive portion 7b and wire holding portion 7a after being compressed by the upper blade die 31a and lower blade die 31b (if a tensile strength member is included, the total cross-sectional area of the conductor 13 including the tensile strength member) are A3 and A4, respectively, then the compression ratio of the wire holding portion 7a = A4/A1 (%), and the compression ratio of the conductive portion 7b = A3/A1 (%).

In addition, since the tensile strength member 17 is stronger and less likely to deform than the conductor 13, when compressed, the cross-sectional area of the tensile strength member 17 does not decrease significantly, and deformation (reduction in cross-sectional area) of the conductor 13 mainly progresses.

Here, when the strength member 17 is formed from multiple strands, each strand is finer than the conductor that makes up the conductor 13, making it difficult to clearly distinguish between the strength member strands and the gaps between them. For this reason, the cross-sectional area of the strength member 17 before crimping is defined as the area of the region of the strength member surrounded by the conductor 13. In this case, in the early stages of compression, the strength member deforms so as to reduce the gaps between the strength member strands, while the conductor 13 deforms. In the later stages of compression, there is almost no reduction in the cross-sectional area of the strength member, and the cross-sectional area of the conductor 13 mainly decreases. For this reason, the compression ratio of the conductor 13 after crimping is equal to or less than the apparent compression ratio of the region where the strength member 17 is located. Note that the area ratio of the conductor 13 to the strength member 17 after compression varies depending on the compression ratio of the entire electric wire.

In addition, as the tension wires move during compression, the outer shape of the tension member 17 becomes uneven, increasing the contact area between the conductor 13 and the tension member 17 and increasing the frictional force. This makes it easier for tension to be transmitted from the conductor 13 to the tension member 17, and is expected to increase the strength of the conductor 13 when tension is applied.

Furthermore, because the tensile strength member 17 deforms less than the conductor 13, it is less likely to break due to a reduction in cross-sectional area. In particular, because the conductor crimping portion 7 is tubular, the conductor 13 is compressed from all sides, and the conductor 13 is positioned between the tensile strength member 17 and the conductor crimping portion 7. Since the tensile strength member 17 and the conductor crimping portion 7 do not come into contact with each other, the tensile strength member 17 is not damaged.

When compressed, some of the wires constituting the strength member 17 may get caught between the conductor wires 13, causing part of the strength member 17 to come into contact with the conductor crimping portion 7. As mentioned above, it is desirable that the strength member 17 and the conductor crimping portion 7 do not come into contact, but it is acceptable for part of the strength member 17 to come into slight contact with the conductor crimping portion 7. For example, if the perimeter of the strength member 17 in contact with the conductor crimping portion 7 is 30% or less of the total perimeter of the strength member 17 in any cross section, damage to the strength member 17 can be suppressed.

As described above, according to this embodiment, the conductor crimping portion 7 has a wire holding portion 7a and a conductive portion 7b, so the wire holding portion 7a can be crimped at a compression rate appropriate for ensuring connection strength, and the conductive portion 7b can be crimped at a compression rate appropriate for ensuring conductivity. In other words, the compression rates (amounts of compression) of the wire holding portion 7a and the conductive portion 7b can be made different, so each portion can be crimped at a compression rate appropriate for its purpose.

More specifically, by making the tip end side (terminal body 3 side) of the conductor crimping portion 7 the wire holding portion 7a, stronger crimping can be performed, ensuring high connection strength. At this time, it is acceptable for part of the conductor wire 13 to break. On the other hand, because the conductive portion 7b is located on the rear end side (covering portion 15 side) of the conductor crimping portion 7, even if part of the conductor wire 13 breaks at the wire holding portion 7a, electrical continuity between the covered conductor wire 11 and the terminal 1 can be ensured.

In addition, the crimping process can be performed in the same way as for crimping a regular electric wire with a terminal, making the process easy. In particular, it can also be applied to coated conductor wires 11 that include a tensile strength member 17, ensuring high connection strength even with a thin coated conductor wire 11.

In this case, both the tension member 17 and the conductor 13 are crimped together by the wire holding portion 7a, eliminating the need to crimp the tension member 17 and the conductor 13 separately, making the crimping process easier. Furthermore, in the case of a coated conductor 11 that includes a tension member 17, by placing the tension member 17 approximately in the center of the cross section and the conductor 13 on the outer periphery, the terminal 1 and the conductor 13 can be reliably crimped together during crimping, ensuring contact between the terminal 1 and the conductor 13.

Furthermore, because the conductor crimping portion 7 is approximately cylindrical, it can be reliably crimped from the entire 360° circumference of the conductor 13. This prevents localized stress (deformation) from occurring in the conductor 13 during crimping.

When the conductor crimping portion 7 of the insulated conductor 11, in which the conductor 13 is arranged around the strength member 17, is crimped, a compressive stress acts radially inside the conductor crimping portion 7. If this compressive stress is small, the frictional force at the contact surface between the conductor 13 and the strength member 17 will be smaller than the frictional force at the contact surface between the terminal 1 and the conductor 13. For this reason, when a tensile load is applied to the terminal-attached electric wire 10, the load will be concentrated on the conductor 13, making the conductor 13 more likely to break.

On the other hand, slippage occurs at the contact surface between the conductor 13 and the tension member 17, preventing compressive stress from acting on the tension member 17, which could result in the tension member 17 coming out without breaking, and the tension member 17 not fully demonstrating its tensile strength. To prevent this phenomenon and obtain sufficient compressive stress through crimping, the frictional force between the conductor 13 and the tension member 17 can be increased. For example, by providing irregularities on the inner surface of the conductor crimping portion 7, the compressive stress on the tension member 17 can be partially increased, preventing it from coming out.

Furthermore, if the conductor crimping portion 7 is cylindrical and has a brazed portion at the joint, a brazed portion with low hardness will have a smaller compressive stress on the conductor 13, making it easier for the tensile strength member 17 to be pulled out. For this reason, it is desirable to either remove the brazed portion, or to eliminate the brazed portion and make the hardness of the joint formed at the conductor crimping portion 7 equal to the hardness of the material in the conductor crimping portion 7.

Second Embodiment
Next, a second embodiment will be described. Fig. 8 is a perspective view of a terminal 1a according to the second embodiment before the coated conductor wire 11 is crimped. In the following description, components that perform the same functions as those in the first embodiment are designated by the same reference numerals as those in Figs. 1 to 7, and redundant description will be omitted.

Terminal 1a has a configuration similar to that of Terminal 1, but differs in the shape of the crimping portion 5. Terminal 1a has a slit formed between the conductor crimping portion 7 and the insulation crimping portion 9. In other words, the conductor crimping portion 7 and the insulation crimping portion 9 are formed separately.

Terminal 1a can also be crimped in the same way as terminal 1. In this case, it is sufficient to crimp it so that the end of the covering portion 15 is positioned in the slit between the conductor crimping portion 7 and the covering crimping portion 9. In this way, by crimping the conductor crimping portion 7 to form the wire holding portion 7a and the conductive portion 7b, the same effect as in the first embodiment can be achieved.

(Third embodiment)
Next, a third embodiment will be described. Fig. 9 is a perspective view of a terminal 1b according to the third embodiment before crimping. Terminal 1b has substantially the same configuration as terminal 1a, but differs in the shape of the crimping portion 5. Before crimping, terminal 1b has a wire holding portion 7a at the tip end of the conductor crimping portion 7, and a conductive portion 7b at the rear end of the conductor crimping portion 7 for establishing electrical continuity with the conductor, with the wire holding portion 7a and the conductive portion 7b separated by a slit. In this case, the wire holding portion 7a and the conductive portion 7b may have different diameters.

Terminal 1b can be crimped in the same way as terminal 1, etc. In this way, by forming and crimping the wire holding portion 7a and conductive portion 7b in the conductor crimping portion 7, the same effects as in the first embodiment can be achieved.

(Fourth embodiment)
Next, a fourth embodiment will be described. Fig. 10 is a perspective view of a terminal 1c according to the fourth embodiment before crimping. Terminal 1c has a configuration substantially similar to terminal 1a, but differs in the shape of the crimping portion 5. Terminal 1c has an open-barrel insulation crimping portion 9. That is, the conductor crimping portion 7 is tubular, and the insulation crimping portion 9 is open-barrel, with the two having different shapes. In this way, the insulation crimping portion 9 may be open-barrel rather than tubular.

Terminal 1c can be crimped in the same way as terminal 1, etc. In other words, by forming the wire holding portion 7a and the conductive portion 7b in the conductor crimping portion 7 and crimping them, the same effects as in the first embodiment can be achieved.

Fifth Embodiment
Next, a fifth embodiment will be described. Fig. 11 is a perspective view of a terminal 1d according to the fifth embodiment before crimping. Terminal 1d has a configuration substantially similar to that of terminal 1c, but differs in the shape of the crimping portion 5. Terminal 1d has a tubular conductor crimping portion 7 in which a slit is formed between the wire holding portion 7a and the conductive portion 7b. That is, before crimping, the wire holding portion 7a and the conductive portion 7b are formed separately. In this case, the wire holding portion 7a and the conductive portion 7b may have different diameters.

Terminal 1d can be crimped in the same way as terminal 1, etc. In this way, by forming and crimping the wire holding portion 7a and conductive portion 7b in the conductor crimping portion 7, the same effects as in the first embodiment can be achieved.

Sixth Embodiment
Next, a sixth embodiment will be described. Fig. 12 is a perspective view of a terminal 1e according to the sixth embodiment before crimping. Terminal 1e has a configuration substantially similar to terminal 1d, but differs in the shape of the crimping portion 5. Terminal 1e differs in that the wire holding portion 7a of the conductor crimping portion 7 is tubular, and the conductive portion 7b and the insulation crimping portion 9 of the conductor crimping portion 7 are open barrel types. As such, as long as at least a portion of the conductor crimping portion 7 is tubular and closed in the circumferential direction, other portions may be open barrel types.

Terminal 1e can be crimped in the same way as terminal 1, etc. Figure 13 is a plan view showing a terminal-attached electric wire 10a in which terminal 1e and covered conductor wire 11 are crimped. In terminal 1e, the tubular electric wire holding portion 7a, open-barrel-shaped conductive portion 7b, and insulation crimping portion 9 are each crimped to each portion of the covered conductor wire 11. In this case, as mentioned above, the compression rate of electric wire holding portion 7a is smaller than that of conductive portion 7b.

Here, at least one pair of opposing barrel pieces are folded in the open-barrel conductive portion 7b and the insulation crimping portion 9, crimping the conductor 13 and the insulation 15, respectively. In this embodiment, the opposing barrel pieces are arranged in a staggered pattern, offset from each other in the axial direction of the crimping portion.

As described above, open-barrel crimping sections with barrel pieces arranged in a staggered pattern generally enable reliable crimping by tightly contacting the barrel pieces with the crimped object without damaging the object, but they have the characteristic of being difficult to achieve high connection strength. For this reason, in this embodiment, the wire holding section 7a is tubular and strongly crimped to ensure high connection strength, and the conductive section 7b is a staggered open-barrel type, ensuring reliable continuity with the conductor 13 without damaging the internal conductor 13.

In this way, by forming and crimping the wire holding portion 7a and the conductive portion 7b in the wire crimping portion 7, it is possible to obtain the same effects as in the first embodiment, etc. In particular, by making at least a portion of the wire crimping portion 7, such as the wire holding portion 7a that requires high connection strength, into a circumferentially closed tube shape, it is possible to obtain high holding force, and by making the conductive portion 7b into an open barrel shape, it is possible to reduce electrical resistance.

In addition, the barrel pieces of at least one of the conductive portion 7b and the coating crimping portion 9 may be arranged in opposing positions, rather than in a staggered arrangement, and the barrel pieces may be crimped so that they overlap each other. In this case, rather than butting the tips of the opposing barrel pieces together, the opposing barrel pieces are overlapped and crimped so that one barrel piece encases the other barrel piece. In this way, there are no particular limitations on the open barrel type crimping format.

Various types of electric wires with terminals were created, and the electrical properties (electrical resistance), mechanical properties (connection strength), and manufacturing workability of the crimped portion were evaluated. Electrical properties were evaluated by measuring the electrical resistance between the terminal and the coated conductor. Mechanical properties were evaluated by pulling the coated conductor from the terminal and measuring the tensile strength based on the load applied when the coated conductor was pulled out. Manufacturing workability was also evaluated based on the ease of inserting the coated conductor into the terminal. The various conditions and evaluation results are shown in Tables 1 to 4.

The cross-sectional area of the electric wire is the total cross-sectional area of the conductor. The number of strands is the number of conducting wires. Wires with a "-" tension member do not have a tension member, as shown in Figures 3(a) and 3(b). Wires with a "Yes" tension member have a tension member in the center, with conducting wires arranged around the tension member's outer periphery, as shown in Figure 3(c). In both cases, multiple annealed copper conducting wires were used, twisted together.

"Circular compression" of the terminal processing section involves compressing the conductor from the outer periphery, as shown in Figure 5(c), while "circular compression + batch plating" involves forming a plating layer all at once from the outer periphery.

The "tubular split type" terminal shape is similar to terminal 1b shown in Figure 9, the "tubular integrated type" is similar to terminal 1 shown in Figure 4, and the "tubular/open barrel type" is similar to terminal 1c shown in Figure 10.

The crimping blade dies are blade dies that simultaneously crimp the conductor crimping portion and the insulation crimping portion. Those with a "strong compression/weak compression (two-stage)" conductor crimping portion have two stages, conductor crimping blade dies 32a and 32b, with one stage (the leading end) being strongly compressed and the other stage (the trailing end) being weakly compressed, as shown in Figure 7. In contrast, those with a "single stage" crimp the conductor crimping portion at a constant compression rate, and are classified as "weak compression," "medium compression," or "strong compression" depending on the compression rate. A compression rate of 40% or more but less than 50% is considered strong compression, a compression rate of 50% or more but less than 60% is considered medium compression, and a compression rate of 60% or more but less than 90% is considered weak compression.

The resistance value is the electrical resistance between the tip of the terminal and the rear end of a 100 mm long covered conductor. The tensile strength is the load when the covered conductor is pulled out of the terminal. Regarding terminal insertion ease, if it was easy to insert the covered conductor into the crimped portion of the terminal, it was given a rating of ○, and if it was somewhat difficult, it was given a rating of △.

As can be seen from Tables 1 to 3, all of Examples 1 to 19, in which the conductor crimping portion was crimped in two stages, were able to achieve both high resistance and high tensile strength. For example, when the conductor cross-sectional area was 1.25 sq, the resistance was 2 mΩ/100 mm or less and a tensile strength of 300 N or more was achieved. Furthermore, when the conductor cross-sectional area was 0.35 sq, the resistance was 10 mΩ/100 mm or less and a tensile strength of 70 N or more was achieved. Furthermore, when the conductor cross-sectional area was 0.13 sq, the resistance was 30 mΩ/100 mm or less and a tensile strength of 30 N or more was achieved. Furthermore, when the conductor cross-sectional area was 0.08 sq, the resistance was 50 mΩ/100 mm or less and a tensile strength of 30 N or more was achieved. Furthermore, when a tensile member was included, even a 0.05 sq cross-sectional area achieved a resistance of 40 mΩ/100 mm or less and a tensile strength of 60 N or more.

In addition, in Examples 8 to 14, which have an open-barrel type insulation crimping portion, the conductor can first be placed in the insulation crimping portion from above, and then the conductor can be inserted into the tubular conductor crimping portion. This makes it easy to position the conductor relative to the conductor crimping portion, and the conductor can be easily inserted into the terminal.

On the other hand, in Comparative Example 1, which had a conductor cross-sectional area of 1.25 sq m, the entire conductor crimped portion was compressed more strongly than in Examples 1 and 8, resulting in a higher resistance of 2.5 mΩ/100 mm due to conductor breakage. In Comparative Example 2, which had a conductor cross-sectional area of 0.3 sq m, the entire conductor crimped portion was compressed less strongly than in Examples 3 and 9, resulting in a weaker conductor retention force and a lower tensile strength of 59 N. In Comparative Example 3, which had a conductor cross-sectional area of 0.13 sq m, the entire conductor crimped portion was compressed moderately compared to Examples 4, 11, 15, and 16, resulting in a higher resistance of 34 mΩ/100 mm and a lower tensile strength of 19 N. In Comparative Examples 4 and 5, which had a conductor cross-sectional area of 0.05 sq m and had a tensile member, the entire conductor crimped portion was compressed more strongly than in Examples 5 to 7 and 12 to 14, resulting in a higher resistance of 100 mΩ/100 mm or more.

In this way, by dividing the conductor crimping portion into two parts, the wire holding portion and the conductive portion, and crimping each under different conditions, it is possible to satisfy the requirements for both electrical resistance and connection strength. Note that the method is not limited to changing the compression ratio, as long as the crimping can be performed so that the connection strength of the wire holding portion is higher than that of the conductive portion. For example, other methods may be used, such as changing the cross-sectional shape of the wire holding portion after crimping.

Although an embodiment of the present invention has been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art could conceive of various modifications or alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

For example, while the above description illustrates an example in which the conductors 13 are arranged in one layer around the periphery of the reinforcing member 17, the arrangement of the conductors 13 is not limited to this. As long as the conductors 13 are arranged on the outer periphery of the reinforcing member 17, the conductors 13 may be arranged in two layers around the reinforcing member 17 as shown in FIG. 14(a), or in three layers around the reinforcing member 17 as shown in FIG. 14(b). Furthermore, from the standpoint of the conductivity and strength of the conductors 13 themselves, the number of conductors 13 in the layer in contact with the reinforcing member 17 should be three or more, and preferably 20 or less. For example, the number may be 12 or 14, as shown in FIG. 5, FIG. 6, FIG. 14, etc., or it may be six or eight.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 1d, 1e... Terminal 3... Terminal body 4... Transition portion 5... Crimping portion 7... Conductor crimping portion 7a... Wire holding portion 7b... Conductive portion 9... Insulation crimping portion 10, 10a... Terminal-attached wire 11... Insulated conductor wire 13... Conductor wire 15... Insulation portion 17... Tensile member 19... End processing portion 21... Plating layer 31a... Upper blade mold 31b... Lower blade mold 32a, 32b... Conductor crimping blade mold 34... Insulation crimping blade mold

Claims (11)

A terminal-attached electric wire in which a coated conductor wire and a terminal are electrically connected,
the terminal includes a conductor crimping portion to which the conductor exposed from the coating portion at the tip of the coated conductor wire is crimped, and a coating crimping portion to which the coating portion of the coated conductor wire is crimped,
At least a portion of the conductor crimping portion has a tubular shape that is closed in the circumferential direction,
a wire holding portion is provided at a front end side of the conductor crimping portion, and a conductive portion for establishing electrical continuity with the conductor is formed at a rear end side of the conductor crimping portion, and the wire holding portion and the conductive portion have different compression ratios,
The coated conductor wire includes a plurality of the conductor wires and at least one strength member,
The wire holding portion holds both the conductor wire, at least a portion of which is broken, and the tension member,
The conductive wire is not broken at the conductive portion,
The electrical resistance of the conductor in the conductive portion is lower than the electrical resistance of the conductor in the wire holding portion.
A terminal-attached electric wire characterized by: The electric wire with terminal described in claim 1, characterized in that the inner surface of the conductor crimping portion is provided with irregularities. the strength members include fibers;
3. The electric wire with terminal according to claim 1, wherein a part of the fibers of the tension member enters into a gap in the broken conductor. The electric wire with terminal described in claim 1, characterized in that the compression rate of the electric wire holding portion is smaller than the compression rate of the conductive portion. An electric wire with terminal according to any one of claims 1 to 4, characterized in that, in a cross section perpendicular to the longitudinal direction of the covered conductor, the strength member is located approximately at the center of the covered conductor, and the conductor is arranged around the outer periphery of the strength member. The electric wire with terminal described in claim 5, characterized in that the conductor wire is twisted in the longitudinal direction of the coated conductor wire. An electric wire with terminal according to any one of claims 1 to 6, characterized in that at least the tip of the conductor is compressed from the outer periphery or the entire conductor is plated from the outer periphery. The electric wire with terminal according to any one of claims 1 to 7, wherein the cross-sectional area of the conductor is 0.3 mm2 or ^less . The electric wire with terminal described in claim 1, characterized in that the compression rate of the insulation crimping portion is smaller than the compression rate of the conductive portion. A wire harness comprising a plurality of terminal-attached electric wires integrated together, including the terminal-attached electric wire described in any one of claims 1 to 9. A method for manufacturing an electric wire with a terminal using a terminal crimping blade,
The terminal-attached wire is
The coated conductor wire and the terminal are electrically connected,
the terminal includes a conductor crimping portion to which the conductor exposed from the coating portion at the tip of the coated conductor wire is crimped, and a coating crimping portion to which the coating portion of the coated conductor wire is crimped,
At least a portion of the conductor crimping portion has a tubular shape that is closed in the circumferential direction,
a wire holding portion is provided at a front end side of the conductor crimping portion, and a conductive portion for establishing electrical continuity with the conductor is formed at a rear end side of the conductor crimping portion, and the wire holding portion and the conductive portion have different compression ratios,
The coated conductor wire includes a plurality of the conductor wires and at least one strength member,
The terminal crimping blade mold is
It has an upper blade type and a lower blade type,
the upper blade die and the lower blade die are formed so that portions corresponding to the conductor crimping portion and the insulation crimping portion have a substantially circular cross section when the terminal is crimped;
a gap between the upper blade die and the lower blade die at a portion corresponding to the electric wire holding portion is formed to be narrower than a gap between the upper blade die and the lower blade die at a portion corresponding to the conductive portion,
a step of engaging the upper blade die and the lower blade die of the terminal crimping blade die to crimp the conductor wire crimping portion and the insulation crimping portion,
In the crimping step, at least a portion of the conductor wire is broken to hold both the conductor wire and the tensile strength member at a portion corresponding to the wire holding portion provided at the front end side of the conductor wire crimping portion, and the conductor wire is not broken at a portion corresponding to the conductive portion formed at the rear end side of the conductor wire crimping portion to ensure conductivity,
The electrical resistance of the conductor in the conductive portion is lower than the electrical resistance of the conductor in the wire holding portion.
A method for manufacturing an electric wire with a terminal, comprising: