Patent Description:
A wire harness for motor vehicles is a bundle of coated conductive wires in which a conductor is connected to a crimp terminal. The wire harness is often wired as a signal wire inside a vehicle, for example. The common coated conductive wire and the crimp terminal are connected to each other by removing a coating at a tip end of the coated conductive wire, crimping the exposed conductor at a conductive wire crimp part, and crimping a coating at a coating crimp part. At this time, an oxide film of poor conductivity is formed on a surface of the conductor. The oxide film, however, can be broken by strong compression when crimping the conductive wire crimp part. Thus, strands forming the conductor are in contact with the conductive wire crimp part of the crimp terminal, thereby achieving conduction with the crimp terminal.

However, particularly for wire harnesses used in vehicles, electric wires having smaller diameters than conventional wires are sometimes used for weight reduction, and there has been a demand for electric wires having thin diameters of <NUM> sq (sq: mm<NUM>) or less. In a case of using such thin electric wires, there is a problem that tensile strength at a connection part may be significantly lowered because of breaking of the strands, or damages given to the strands, due to excessive compression. However, if less compression is given, the breaking of the oxide film is insufficient as mentioned above, which raises a problem of an increase in resistance at the connection part.

That is, strong compression may damage the strands, which is likely to lower strength at the crimp part; and the weak compression increases the resistance at the crimp part since the compression is insufficient to break the oxide film, and, in addition, the weak compression fails to give enough strength at the crimp part and fall-out due to insufficient crimping occurs. As above, it is difficult, particularly for the coated electric wire having a thin diameter, to control balance between conductivity and tensile strength by varying compression rates only. Thus, a connector that can easily control the balance between conductivity and tensile strength in just one crimping has been awaited.

As a countermeasure, a use of an electric wire including a tension member has been considered. For example, in a case of using an electric wire formed of a conductor having tensile strength of approximately <NUM> N, to obtain tensile strength of <NUM> N or more, which is a requirement for an electric wire for motor vehicles, <CIT> has proposed an electric wire including a tension member in which a conductive wire is spirally wound around an outer periphery of the metal or non-metal tension member. Such the electric wire is produced by a method in which a conductor is peeled in stages to expose the tension member and inserted into a sleeve, the tension member is then crimped by a steel-made clamp and further unified as one body by using curable resin such as an adhesive agent, and the conductor part is crimped by an aluminum clamp.

Also, <CIT> has proposed a coated electric wire including a conductor being formed of a plurality of strands that are bundled together, and a fibrous tension member being disposed in valley parts among the strands on an outer periphery side of the conductor and an inner periphery side of a coating material.

<CIT> disclose a solderless connector for connection to a stranded wire e.g. of aluminum, comprises a ferrule in which is positioned a resilient core e.g. of nylon having a greater resiliency than the ferrule so that when the latter is crimped on to the wire the core is also compressed and on release of the crimping pressure maintains the wire and ferrule in good contact. The core has a head around which one end of the ferrule is crimped to form a seal, the other end of the ferrule carrying a metal sleeve having a plastic liner which on crimping of the sleeve on to the insulation of the wire, also forms a seal. The sleeve may be continued inside the ferrule as a continuous thimble against the closed end of which the head abuts.

<CIT> addresses the problem of how to provide an electric wire for an automobile having a lighter weight, a smaller diameter, and with excellent tensile strength as well as excellent flexing characteristics, as compared with current electric wires for automobiles. The document proposess an electric wire for an automobile, which is provided with a core wire part with four stainless-steel strands of the same diameter wound around with a cross-section shape of the stainless-steel strands as a whole nearly circular, and an outer periphery wire part made by arranging at least eight copper strands of the same diameter tightly adhered with each other in a single layer around the core wire part. Especially, formation of the cross-section shape of the four stainless-steel strands as a whole of the core wire part is made by compression of the stainless-steel strands before arranging of the outer periphery wire part from outside toward the center.

<CIT> discloses: a crimp terminal includes an F-type crimp portion and a C-type crimp portion the F-type crimp portion having a first and a second barrel tab and for crimping a tip end of a complex stranded wire, the first and the second barrel tab and having an identical length, the F-type crimp portion being adapted to have distal ends of the first and the second barrel tab and put together and pushed into the tip end of the complex stranded wire to be crimped, the C-type crimp portion having a third barrel tab for crimping the complex stranded wire, the C-type crimp portion having the third barrel tab wound in a C-form on an outer periphery of the complex stranded wire to be crimped.

However, in both <CIT> and <CIT>, when a coated conductive wire having a large diameter is used and connected to a crimp terminal, for example, crimping at the conductive wire crimp part is possible with a compression rate that can satisfy both the connection strength and the connective resistance. However, if the diameter of the electric wire becomes smaller, a scope of crimping conditions that are appropriate for both the connection strength and the electric resistance becomes smaller. This is because obtaining the sufficient connection strength may cause the conductor to fracture and to have the higher connective resistance, and prioritizing the connective resistance may fail to obtain the connection strength, causing the electric wire to come off. Thus, the smaller the electric wire diameter is, the harder it is to satisfy both the connection strength and the electric resistance.

Also, in <CIT> for example, the tension member is damaged and tensile strength is lowered when the compression rate is low at the time of crimping (i.e., strong compression); and the resistance at the crimp part is increased when the compression rate is high (i.e., weak compression). In particular, when crimping with an open barrel shape, the conductor and the tension member may be disarranged at the time of being crimped, which raises a problem of lowering tensile strength and increasing the resistance at the crimp part. Also, to connect a conventional electric wire including a tension member, peeling in stages and crimping steps for crimping the tension member and the conductive wire are necessary. This increases the number of components and operational steps, which raises cost. In particular, the peeling in stages itself becomes harder as a diameter of the electric wire decreases. As above, <CIT> has problems that manufacturing steps are complex and thus processing cost is high.

Also, <CIT> discloses an example in which strength is improved without impairing electrical properties by providing a fibrous tension member between conductive wires. However, when crimping an electric wire in <CIT>, the tension member enters into gaps between the conductive wire and the terminal, and this may increase the resistance at the crimp part. Even if the tension member is a conductor, with a change in temperature, there may be a gap generated between the tension member and the conductor due to a difference in heat expansion rates. Thus, <CIT>, similarly to <CIT>, cannot solve the problem that the tension member is damaged and tensile strength is lowered when the compression rate is low at the time of crimping, and the resistance at the crimp part is increased when the compression rate is high at the time of crimping.

The present invention is made in view of the above problems. It is an object of the present invention to provide a terminal-equipped electric wire and the like that can achieve an excellent crimping workability and satisfy both connection strength and connective resistance.

To achieve the above object, a first aspect of the present invention is a terminal-equipped electric wire in which a coated conductive wire and a terminal are electrically connected to each other. The coated conductive wire includes a tension member and a conductive wire that is disposed on an outer periphery of the tension member and is formed of a plurality of conductors. A cross-sectional area of the conductive wire is <NUM> mm2 or less, and tensile strength of the tension member is greater than tensile strength of the conductor. The terminal includes a conductive wire crimp part and a coating crimp part. The conductive wire being exposed from a coating at a tip end of the coated conductive wire is crimped at the conductive wire crimp part, and the coating of the coated conductive wire is crimped at the coating crimp part. The conductive wire is crimped at the conductive wire crimp part from an entire circumference of a circumferential direction of the conductive wire. The tension member comprises a plurality of strands so that an unevenness is formed on an outer periphery surface of the tension member. The conductive wire is crimped at the conductive wire crimp part from an entire circumference of the circumferential direction of the conductive wire at a predetermined position in an axial direction. The conductive wire deforms so as to be fitted into the unevenness formed on an outer periphery surface of the tension member thereby preventing the conductive wire from being excessively crashed and broken.

Preferably, a compression rate of the conductive wire is equal to or less than an apparent compression rate of a region on which the tension member is disposed.

The conductive wire may be twisted on the outer periphery of the tension member.

At least a tip end part of the conductive wire may be compressed from an outer periphery side.

The plurality of conductors may be plated.

Preferably, the conductive wire crimp part is not in contact with the tension member.

The cross-sectional area of the conductive wire may be <NUM> mm2 or less.

According to the first aspect of the present invention, the conductive wire is disposed on an outer periphery part of the tension member in a cross section that is perpendicular to a longitudinal direction of the coated conductive wire. This can make certain that the conductive wire and a conductor crimp part are in contact and conductive with each other when the conductive wire is crimped at the conductive wire crimp part. Also, crimping from the entire circumference of the conductive wire at the conductive wire crimp part can eliminate local stress (deformation) applied to the conductive wire at the time of crimping, and, at the same time, can provide a contacting area between the conductive wire and the conductive wire crimp part.

Also, the tension member at the center can improve tensile strength of the conductive wire. At this time, there is no need to connect the tension member and the conductive wire by using separate clamps as in conventional techniques. This reduces the number of components used and facilitates the connection operation.

The above-mentioned effects are particularly effective when using the small-diameter coated conductive wire in which the cross-sectional area of the conductive wire is <NUM> mm2 or less, or as small as <NUM> mm2 or less.

Also, since tensile strength of the tension member is greater than that of the conductive wire, deformation of the tension member at the time of compression is suppressed, which can suppress lowering of tensile strength of the electric wire. At this time, if the tension member is formed of a plurality of strands, unevenness is formed at the time of compression on the outer periphery part of the tension member because of the strands. Thus, even with an equal amount of deformation, the conductive wire can deform while a part of the conductive wire enters into the unevenness and this can prevent the conductive wire from being excessively crashed compared to a case in which the conductive wire deforms on an outer periphery surface of one single tension member.

Also, when crimping the conductive wire crimp part, tensile strength of the tension member is strong, and thus the compression rate of the conductive wire can be equal to or less than the apparent compression rate of the region on which the tension member is disposed. This can suppress deformation of the tension member while compressing and deforming the conductive wire with certainty.

Also, if the conductive wire is twisted on the outer periphery of the tension member, disarrangement of the conductive wire can be suppressed.

Similarly, compressing the tip end part of the conductive wire from the outer periphery side to form a processed end part can suppress disarrangement of the conductive wire when inserting the tip end of the conductive wire into the pipe-shaped conductive wire crimp part.

Also, plating a surface of the conductor with conductive metal is effective in improving conductivity and tensile strength. This is also effective in improving workability since disarrangement of the conductor strands is suppressed at the time of crimping operation of the electric wire.

Also, the conductive wire is crimped at the conductive wire crimp part at the predetermined position in the axial direction from the entire circumference. This can suppress local stress applied onto the conductive wire with more certainty at the time of crimping and, at the same time, can provide the contacting area between the conductive wire and the conductive wire crimp part.

Also, crimping in such a way that the conductive wire crimp part is not in contact with the tension member can suppress disarrangement of the conducive wire, thereby ensuring that the conductive wire and the conductive wire crimp part are in contact with each other, and can compress the conductive wire and the tension member with certainty. For example, when crimping with an open-barrel shape with barrel pieces digging into the center part of the cross section, the cross-sectional shape of the electric wire may change drastically, and this inhibits lowering of both the compression rate of the conductive wire and the compression rate of the tension member, which makes it difficult to achieve the desired performance. Also, by not letting the conductive wire crimp part come into contact with the tension member, the tension member can be prevented from getting damaged by the conductive wire crimp part.

A second aspect of the present invention is a wire harness in which a plurality of terminal-equipped electric wires, including the terminal-equipped electric wire according to the first aspect of the present invention, are unified together as one body.

According to the second aspect of the present invention, the wire harness, which is a bundle of a plurality of small-diameter electric wires, can be obtained.

The present invention can provide a terminal-equipped electric wire and the like that can achieve an excellent crimping workability and satisfy both connection strength and connective resistance.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. <FIG> is a perspective view showing a terminal-equipped electric wire <NUM>, <FIG> is a cross-sectional view of the terminal-equipped electric wire <NUM> taken along an axial direction, and <FIG> is a cross-sectional view of a conductive wire crimp part <NUM> taken along a diameter direction. The terminal-equipped electric wire <NUM> includes a terminal <NUM> and a coated conductive wire <NUM> that are electrically connected to each other.

The coated conductive wire <NUM> is formed of a conductive wire <NUM>, which is made of copper, copper alloy metal, aluminum, or aluminum alloy metal, for example, and a coating <NUM>, which coats the conductive wire <NUM>. That is, the coated conductive wire <NUM> includes the coating <NUM> and the conductive wire <NUM> being exposed from a tip end of the coating <NUM>.

The terminal <NUM> is made of copper, copper alloy metal, aluminum, or aluminum alloy metal, for example. The coated conductive wire <NUM> is connected to the terminal <NUM>. The terminal <NUM> is formed of a terminal body <NUM> and a crimp part <NUM> that are joined together via a transition part <NUM>.

The terminal body <NUM> is made by forming a predetermined shaped plate-like material into a tubular body having a rectangular cross section. The terminal body <NUM> includes an elastic contacting piece that is formed by folding the plate-like material into the rectangular tubular body. A male terminal or the like is inserted from a front-end part of the terminal body <NUM> to be connected. In the descriptions hereinafter, examples in which the terminal body <NUM> is a female-type terminal allowing an insertion tab of a male-type terminal etc., of which illustrations are omitted, to be inserted. However, detail shapes of the terminal body <NUM> in the present invention are not particularly limited. For examples, instead of the female-type terminal body <NUM>, an insertion tab of a male-type terminal may be provided, or, alternatively, a bolt fastening part such as a ring terminal may be provided.

The crimp part <NUM> of the terminal <NUM> is a part to which the coated conductive wire <NUM> is crimped. The crimp part <NUM> includes a conductive wire crimp part <NUM> that crimps the conductive wire <NUM> exposing from the coating <NUM> at a front-end side of the coated conductive wire <NUM>, and a coating crimp part <NUM> that crimps the coating <NUM> of the coated conductive wire <NUM>. That is, the conductive wire <NUM> being exposed by peeling the coating <NUM> is crimped by the conductive wire crimp part <NUM>, thereby electrically connecting the conductive wire <NUM> and the terminal <NUM> with each other. Also, the coating <NUM> of the coated conductive wire <NUM> is crimped by the coating crimp part <NUM> of the terminal <NUM>. In the present embodiment, each of the conductive wire crimp part <NUM> and the coating crimp part <NUM> is formed in a pipe shape being closed in a circumferential direction (in a substantially cylindrical shape).

Although illustrations are omitted, serrations may be provided in a width direction (a direction perpendicular to a longitudinal direction) at a part of an inner surface of the conductive wire crimp part <NUM>. The serrations formed in this way can easily break an oxide film on a surface of the conductive wire <NUM>, and also can increase a contacting area with the conductive wire <NUM> at the time of crimping the conductive wire <NUM>.

As shown in <FIG>, the coated conductive wire <NUM> includes a tension member <NUM>, which is disposed at a substantially center of a cross section, and the conductive wire <NUM>, which is formed of a plurality of conductors disposed on an outer periphery of the tension member <NUM>. The tension member <NUM> is a member that receives tensile force when a tensile load is applied. Although details will be described below, the tension member <NUM> includes a plurality of strands. Also, on the outer periphery of the tension member <NUM>, the conductive wire <NUM> may be spirally twisted together along the longitudinal direction of the coated conductive wire <NUM>. At this time, the each conductive wire <NUM> (strands) disposed on the outer periphery of the tension member <NUM> may have the same cross-sectional area and the same shape. For the conductive wire <NUM>, annealed copper wires, hard-drawn copper wires, copper alloy metal wires, aluminum wires, or aluminum alloy metal wires may be used, for example. However, from a viewpoint of electrical conductivity, annealed copper wires are preferable.

As mentioned above, the conductive wire crimp part <NUM> is in a pipe shape. Thus, at a predetermined position (in a cross section at the predetermined position) in an axial direction of the conductive wire crimp part <NUM>, the conductive wire <NUM> can be crimped by the conductive wire crimp part <NUM> from the entire <NUM>° circumference thereof. That is, the conductive wire <NUM> is crimped at the conductive wire crimp part <NUM> from an entire circumference of a circumferential direction of the conductive wire <NUM>. Thus, an inner surface of the conductive wire crimp part <NUM> is in contact with the conductive wire <NUM> over the entire circumference, which can prevent the conductive wire <NUM> from being applied with local stress (deformation) at the time of crimping.

Here, the present invention is particularly effective when a cross-sectional area of the conductive wire <NUM> (a total of cross-sectional areas of the strands) is <NUM> sq or less. That is, the terminal <NUM> can crimp the conductive wire <NUM> having the cross-sectional area of <NUM> sq or less. Furthermore, the cross-sectional area of the conductive wire <NUM> (the total of cross-sectional areas of the strands) is preferably <NUM> sq or less, and, in such the case, it is preferable that the terminal <NUM> can crimp the conductive wire <NUM> having the cross-sectional area of <NUM> sq or less. Also, the conductive wire <NUM> is used together with the tension member <NUM>, and thus the cross-sectional area of the conductive wire <NUM> may be <NUM> sq or less. Smaller the cross-sectional area of the conductive wire <NUM> is, the larger the effects of the present embodiment. From a viewpoint of obtaining sufficient crimp strength, the cross-sectional area of the conductive wire <NUM> is preferably <NUM> sq or more, and more preferably <NUM> sq or more.

The tension member <NUM> is formed of the plurality of strands, which may be made of metal such as steel, resin, or fiber-reinforced resin. Example for the strands forming the tension member <NUM> include polyparaphenylene benzobis oxazole (PBO) fibers, aramid fibers, carbon steel wires, stainless steel wires, liquid-crystal polyester fibers, glass fibers, and carbon fibers. However, when considering anticorrosion property, non-metal wires are preferable.

Also, it is preferable that tensile strength of the tension member <NUM> is greater than tensile strength of the conductive wire <NUM>. The tensile strength is defined as the maximum stress before breaking while being applied with tensile stress. However, in the present embodiment, tensile strength is regarded as a relative index of tendency to break due to crashing of a material when crimped. That is, compared to the conductive wire <NUM>, the tension member <NUM> is made of a material that is more unlikely to deform by crimping. Furthermore, it is preferable that a Young's modulus of the tension member <NUM> is greater than that of the conductive wire <NUM>, and yield stress (or proof stress) of the tension member <NUM> is greater than that of the conductive wire <NUM>.

Next, a method for manufacturing the terminal-equipped electric wire <NUM> will be described. <FIG> is a perspective view showing the terminal <NUM> and the coated conductive wire <NUM> before crimping. As mentioned above, the terminal <NUM> includes the terminal body <NUM> and the crimp part <NUM>. The crimp part <NUM> includes the conductive wire crimp part <NUM> and the coating crimp part <NUM> that are formed as one body in a substantially cylindrical shape. The crimp part <NUM> may be formed by rolling a plate member, butting end parts thereof to each other, and joining the end parts by welding or brazing in the longitudinal direction, and the terminal <NUM> may be formed by developing a tube-shaped member. Although the conductive wire crimp part <NUM> and the coating crimp part <NUM> may have the same diameter, an inner diameter of the coating crimp part <NUM> may be larger than the inner diameter of the conductive wire crimp part <NUM> as shown in the drawing.

First, as mentioned above, the coating <NUM> at the tip end part of the coated conductive wire <NUM> is peeled off to expose the conductive wire <NUM> at the tip end part. Next, as shown in <FIG>, a processed end part <NUM> may be formed at the tip end part of the conductive wire <NUM> before being inserted into the crimp part <NUM> of the terminal <NUM>. The processed end part <NUM> is a processed part in which the strands of the conductive wire <NUM> are unified so as not to be separated from one another.

As mentioned above, the tension member <NUM> is disposed at the substantially center and the conductive wire <NUM> is disposed on the outer periphery of the tension member <NUM>. The conductive wire <NUM> is formed of the plurality of strands. In such the case, as shown in <FIG>, the processed end part <NUM> can be formed by compressing at least the tip end part of the conductive wire <NUM> from the outer periphery side. Compressing the tip end part of the conductive wire <NUM> from the outer periphery side in this way can prevent the strands from separating from one another and facilitate the insertion of the conductive wire <NUM> into the pipe-shaped crimp part <NUM>.

Also, as shown in <FIG>, the processed end part <NUM> may be formed by collectively plating at least the tip end part of the conductive wire <NUM>, forming a plating layer <NUM>. Plating collectively the tip end part of the conductive wire <NUM> from the outer periphery in this way can prevent the strands from separating from one another and facilitate the insertion of the conductive wire <NUM> into the pipe-shaped crimp part <NUM>.

Note that, when plating collectively the tip end part of the conductive wire <NUM> from the outer periphery, some of the plating methods may cause a temperature rise. If the collective plating is performed on the twisted conductive wire <NUM> using such the plating method, the heat may deteriorate the tension member <NUM>, which may lower tensile strength.

In such the case, as shown in <FIG>, the plating layer <NUM> may be formed for each of the conductors, which are then twisted together on the outer periphery of the tension member <NUM>. Alternatively, as shown in <FIG>, the plating layer <NUM> may be formed for each of the conductors, and then the collective plating process may be further performed on the tip end parts of the plurality of conductors from the outer periphery. In such the case, types of plating for the individual conductors and the collective plating may be different. As mentioned above, the collective plating enables to prevent separation of the conductors. However, when the bundled conductors are plated collectively, there may be partial variations in thickness of the plating caused by shapes or the like of the conductors. The advance preparatory plating for the individual conductor, on the other hand, can reduce such influence, allowing the collective plating to be substantially uniform.

The method for end processing the processed end part <NUM> is not limited to compression or plating. For example, soldering or welding the tip end of the conductive wire <NUM> may be used to prevent separation of the strands. Also, a plurality of end processing methods may be used at the same time, e.g., both compression from the outer periphery and the collective plating.

Next, the coated conductive wire <NUM> with the tip end part being processed as above is inserted into the pipe-shaped crimp part <NUM> of the terminal <NUM> from the rear-end side thereof. When the tip end part of the coated conductive wire <NUM> is inserted into the crimp part <NUM>, the exposed part of the conductive wire <NUM> is positioned inside the conductive wire crimp part <NUM>, and the coating <NUM> is positioned inside the coating crimp part <NUM>. At this time, the tip end of the conductive wire <NUM> may come out of a front end of the conductive wire crimp part <NUM>.

In <FIG>, a view in the middle shows a schematic cross-sectional view taken at the conductive wire crimp part <NUM> before crimping, a view on the left shows a shape of a region of the tension member <NUM>, and a view on the right is an enlarged view of the region of the tension member <NUM>. As mentioned above, the tension member <NUM> is formed by bundling together a plurality of tension member strands 17a. The conductive wire <NUM> is disposed on an outer periphery of the tension member strands 17a.

The cross-sectional area of the conductive wire <NUM> before crimping is the total of the cross-sectional areas of all the conductors, which is also a product standard of the coated conductive wire <NUM>, and the total cross-sectional area can be calculated relatively easily by image analysis of the cross section. On the other hand, each of the tension member strands 17a is thin compared to the conductors forming the conductive wire <NUM>, and it is difficult to clearly distinguish the tension member strands 17a from spaces between the tension member strands 17a. For this reason, an area of a region of the tension member surrounded by the conductive wire <NUM> (A in <FIG>) is taken as the cross-sectional area of the tension member <NUM> before crimping.

<FIG> illustrates views corresponding to <FIG> in the midst of compression. When the compression starts, deformation of the conductive wire <NUM> and the tension member strands 17a progresses. At this time, in early stages of deformation, although there is not much change in the total cross-sectional area of the tension member strands 17a, the spaces between the tension member strands 17a are reduced. Thus, an apparent cross-sectional area of the region of the tension member <NUM> (A1 in <FIG>) is reduced. That is, when crimping the conductive wire crimp part <NUM>, in early stages of the compression, both a compression rate of the conductive wire <NUM> due to deformation and an apparent compression rate of the tension member <NUM> are lowered.

<FIG> illustrates views corresponding to <FIG> after crimping is completed. As mentioned above, the tension member strands 17a have greater strength than the conductive wire <NUM> and are not easily deformed. Thus, after the spaces are reduced, deformation of the conductive wire <NUM> (reduction in the cross section) mainly progresses with very little reduction in the cross-sectional area of the tension member <NUM> (A2 in <FIG>). Note that the apparent cross-sectional area of the tension member <NUM> after compression is calculated by subtracting the cross-sectional area of the conductive wire <NUM> from a cross-sectional area of an inside of the conductive wire crimp part <NUM>. As above, by compressing further from the state shown in <FIG>, reduction in the apparent compression rate of the tension member <NUM> becomes relatively small while reduction in the compression rate of the conductive wire <NUM> progresses mainly.

Here, the compression rate of the conductive wire <NUM> after crimping is equal to or less than the apparent compression rate of the region on which the tension member <NUM> is disposed. The compression rate of the conductive wire <NUM> is A3/A0 (%), wherein A0 refers to the total cross-sectional area of the conductive wire <NUM> before the crimping process (<FIG>) and A3 refers to the total cross-sectional area of the conductive wire <NUM> after compression (<FIG>). Also, the apparent compression rate of the region on which the tension member <NUM> is disposed is A2/A (%), wherein A refers to the cross-sectional area of the tension member region before the crimping process (<FIG>) and A2 refers to the cross-sectional area of the tension member region after compression (<FIG>). Thus, A3/A0 is equal to or less than A2/A. Note that an area ratio of the conductive wire <NUM> to the tension member <NUM> (A3/A2) after compression varies depending on the compression rate of the entire electric wire.

As mentioned above, the conductive wire <NUM> is crimped at the conductive wire crimp part <NUM> from the entire circumference of the circumferential direction of the conductive wire <NUM>. Also, as shown in <FIG>, the tension member <NUM> is formed of the plurality of tension member strands 17a, and thus there is unevenness formed on the outer periphery of the tension member <NUM> (the region). Thus, on an interface between the tension member <NUM> and the conductive wire <NUM>, the conductive wire <NUM> deforms according to the unevenness due to the tension member strands 17a. The unevenness of the outer shape of the tension member <NUM> increases contacting areas between the conductive wire <NUM> and the tension member <NUM>, thereby increasing frictional force. For this reason, when being pulled, force can be easily transmitted from the conductive wire <NUM> to the tension member <NUM> and this is expected to increase strength when a pulling force is applied to the conductive wire <NUM>.

For example, if the tension member <NUM> is a single wire, the interface between the conductive wire <NUM> and the tension member <NUM> is almost flat and smooth. At this time, since the tension member <NUM> is unlikely to deform compared to the conductive wire <NUM>, the conductive wire <NUM> deforms being crashed along the surface of the tension member <NUM>. This may cause the conductive wire <NUM> to become too thin and break. By contrast, if there is unevenness formed on the outer periphery surface of the tension member <NUM>, the conductive wire <NUM> can deform as to be fitted into such unevenness, and this can prevent the conductive wire <NUM> from being excessively crashed and broken.

Since an amount of deformation of the tension member <NUM> (the tension member strands 17a) is small compared to that of the conductive wire <NUM>, fracture of the tension member <NUM> due to the reduction in the cross-sectional area is unlikely to occur. In particular, the tension member <NUM> does not suffer damages since the conductive wire crimp part <NUM> is in a pipe shape and the conductive wire <NUM> is compressed from the entire periphery, and the conductive member <NUM> is disposed between the tension member <NUM> and the conductive wire crimp part <NUM> and the tension member <NUM> and the conductive wire crimp part <NUM> are not in contact with each other.

As shown in <FIG>, there are some cases in which the tension member <NUM>(the tension member strands 17a) enters into the conductive wire <NUM> and a part of the tension member <NUM> comes into contact with the conductive wire crimp part <NUM> (C section in the drawing). As mentioned above, although it is preferable that the tension member <NUM> and the conductive wire crimp part <NUM> are not in contact with each other, the part of the tension member <NUM> may slightly be in contact with the conductive wire crimp part <NUM> as illustrated. For example, damage prevention effects for the tension member <NUM> can be obtained if, on any cross sections, a circumferential length of the tension member <NUM> that is in contact with the conductive wire crimp part <NUM> is <NUM> % or less of the entire outer circumferential length of the tension member <NUM>.

Accordingly, the terminal-equipped electric wire <NUM> can be obtained. Furthermore, a wire harness in which a plurality of terminal-equipped electric wires, including the terminal-equipped electric wire <NUM> obtained as above, are unified together as one body can be obtained.

As described above, according to the present embodiment, the conductive wire <NUM> is crimped at the conductive wire crimp part <NUM> from the entire <NUM>° circumference, and this can prevent local stress (deformation) applied to the conductive wire <NUM> at the time of crimping. It is also possible to perform the crimping without greatly altering the structure in which the tension member <NUM> is disposed in the middle and the conductive wire <NUM> is twisted around the tension member <NUM>. Also, since the conductive wire crimp part <NUM> is in contact with the entire circumference of the conductive wire <NUM>, deterioration in resistance can be prevented.

Also, since tensile strength of the tension member <NUM> is greater than that of the conductive member <NUM>, further stronger crimping can be performed. That is, the strong crimping does not damage the tension member <NUM>, and this can prevent fracture of the coated conductive wire <NUM> at the conductive wire crimp part <NUM>. Also, with the strong crimping, the oxide film of the conductive wire <NUM> can be broken and thus the conductive wire <NUM> and the terminal <NUM> can be in close contact with each other with more certainty. Thus, both the low resistance and the high tensile strength at the crimp part can be achieved. For this reason, the present invention is particularly effective for thin electric wires of <NUM> sq or less.

Also, since the tension member <NUM> is formed of the tension member strands 17a, in the early stages of crimping, deformation of the conductive wire <NUM> and deformation by reducing the spaces between the conductive wire strands 17a progress. Thus, compression force is not applied only to the conductive wire <NUM> and the conductive wire <NUM> is moderately deformed by compression. Also, unevenness is formed on the outer periphery surface of the tension member <NUM> and the conductive wire <NUM> deforms being fitted along the unevenness shape, which prevents excessive crashing of the conductive wire <NUM>.

At the conductive wire crimp part <NUM>, the terminal <NUM> (the conductive wire crimp part <NUM>) is crimped to the conductive wire <NUM> inside, and the conductive wire <NUM> is crimped to the tension member <NUM> (the tension member strands 17a) inside. At this time, if there is a sufficient amount of compression in the conductive wire crimp part <NUM>, frictional force between the terminal <NUM> (the conductive wire crimp part <NUM>) and the conductive wire <NUM> and frictional force between the conductive wire <NUM> and the tension member <NUM> (the tension member strands 17a) are both sufficient, which can achieve high pull-out force. On the other hand, if the amount of compression is insufficient, while it is relatively easy to achieve the friction force between the terminal <NUM> (the conductive wire crimp part <NUM>) and the conductive wire <NUM>, it is difficult to achieve the sufficient frictional force between the conductive wire <NUM> and the tension member <NUM> (the tension member strands 17a), which makes it difficult to obtain the high pull-out force. Thus, it is preferable to obtain a sufficiently large amount of compression (a low compression rate) at the conductive wire crimp part <NUM> within a scope that the conductive wire <NUM> does not break.

Furthermore, in a case, like the present embodiment, in which the conductive wire crimp part <NUM> is in a tubular shape having the joint part being brazed, the compression stress onto the conductive wire <NUM> is small at the brazed part where hardness is low and thus the tension member <NUM> is likely to be pulled out. Thus, it is preferable to eliminate the brazed part, or, alternatively, the joint part formed on the conductive wire crimp part <NUM> preferably has no brazed part and has the same hardness as the material used for the conductive wire crimp part <NUM>.

Next, a second embodiment will be described. <FIG> is a perspective view of a terminal 1a according to the second embodiment before crimping the coated conductive wire <NUM>. In the descriptions below, the same notations used in <FIG> will be used for the structures having the same functions as in the first embodiment, and redundant descriptions will be omitted.

The terminal 1a has approximately the same configuration as the terminal <NUM> except that the crimp part <NUM> is an open-barrel type. The terminal 1a can be crimped similarly as the terminal <NUM>. <FIG> is a plan view showing a terminal-equipped electric wire 10a in which the terminal 1a and the coated conductive wire <NUM> are crimped.

Here, at the open-barrel type conductive wire crimp part <NUM>, at least a pair of facing barrel pieces are folded to crimp the conductive wire <NUM>. At this time, in the present embodiment, the barrel pieces facing each other are arranged in a zigzag, being shifted from each other in regard to an axial direction of the conductive wire crimp part <NUM>. At the coating crimp part <NUM>, facing barrel pieces may be butted against each other, or, similarly to the conductive wire crimp part <NUM>, barrel pieces may be shifted from each other in regard to an axial direction thereof.

In general, such the open-barrel type crimp part having the barrel pieces arranged in a zigzag prevents a crimping target from being damaged, and enables to bring the barrel pieces and the crimping target in close contact to be crimped together with certainty.

However, crimping by zigzag-arranged barrel pieces may not completely crimp the outer periphery of the conductive wire <NUM> over the entire circumference. <FIG> is a cross-sectional view taken along A-A line in <FIG> is a cross-sectional view taken along B-B line in <FIG>. As shown in <FIG>, on the cross section at the predetermined position of the axial direction of the conductive wire crimp part <NUM>, there is a gap <NUM>, which is not crimped by the conductive wire crimp part <NUM>, formed at a part of the circumferential direction.

However, even in such the case, the gaps <NUM> are not aligned along the axial direction of the conductive wire crimp part <NUM> but are formed at different positions of the circumferential direction in the cross-sectional positions, respectively. Thus, it can be said that the conductive wire <NUM> is always crimped over the entire circumference of the circumferential direction at some positions of the axial direction of the conductive wire crimp part <NUM>. For example, the position of the circumferential direction of the gap <NUM> in <FIG> is crimped at the conductive wire crimp part <NUM> in the cross-sectional position in <FIG>, and the position of the circumferential direction of the gap <NUM> in <FIG> is crimped at the conductive wire crimp part <NUM> in the cross-sectional position in <FIG>. In this way, the entire circumference of the circumferential direction of the conductive wire <NUM> may be crimped at some positions of the conductive wire crimp part <NUM>.

As above, the same effects as in the first embodiment etc. can be obtained if the crimp part <NUM> at the conductive wire crimp part <NUM> is an open-barrel type. In addition, with the open-barrel type crimp part <NUM>, disposing the conductive wire <NUM> onto the crimp part <NUM> is easy.

As above, if it is possible to make certain that the conductive wire <NUM> is compressed from the entire circumference at the conductive wire crimp part <NUM>, the conductive wire crimp part <NUM> may be in a shape other than a pipe shape. Also, with the open-barrel type conductive wire crimp part <NUM>, instead of the zigzag arrangement, the barrel pieces may be disposed at the positions such that the barrel pieces face each other at the same position along the axial direction of the conductive wire crimp part <NUM>.

For example, <FIG> is a cross-sectional view showing an example of crimping at the open-barrel type conductive wire crimp part <NUM>, where the barrel pieces are disposed at positions facing each other. In the example illustrated in <FIG>, the barrel pieces are disposed at the positions so that the barrel pieces face each other at the same position along the axial direction of the conductive wire crimp part <NUM>, and the barrel pieces are crimped overlapping each other. That is, the facing barrel pieces are overlapped and crimped as if one of the barrel pieces laps the other barrel piece.

Also, as shown in <FIG>, edges of the barrel pieces that are disposed at positions facing each other may be butted against each other. In such the case, if the edges of the barrel pieces dig inside and come into contact with the tension member <NUM> as shown in <FIG>, arrangement of the conductive wire <NUM> may be disturbed and the tension member <NUM> may fracture, which is not preferable. Thus, although the open-barrel type conductive wire crimp part can crimp the conductive wire <NUM> from the entire circumference, it is still preferable not to let the barrel pieces from digging deep inside to be in contact with the tension member <NUM>.

Various types of terminal-equipped electric wires are produced, and electrical properties (Crimp part Resistance Performance) and mechanical properties (Tensile Strength Performance) as well as anticorrosion properties of the crimp part are evaluated. The coated conductive wire in which the tension member is disposed at the center of the cross section and the conducive wires are twisted together around the outer periphery is used in all cases. As the electrical property, an electric resistance between the terminal and the coated conductive wire is measured and evaluated. As the mechanical property, the coated conductive wire is pulled out from the terminal and a load at the time when the coated conductive wire is pulled out is measured as a tensile strength. Also, Anticorrosion Performance is evaluated by salt-water spraying tests. Materials used are shown in Table <NUM>, and conditions and results of the evaluation are shown in Table <NUM> to Table <NUM>.

"Cross-Sectional Area of Electric Wire" is the total cross-sectional area of the conductors. "Conductor Material" is the material forming the conductive wire, and "Tension member" shows the material forming the tension member. "Fiber" for "Tension member" shows that the tension member is formed by bundling together a plurality of thin strands (fibers), and "Single Wire" refers to a single thick tension member.

"Process for Conductive Wire" refers to the end process of the conductive wire, wherein "Tin Plated" means that the individual conductor is tin plated as shown in <FIG>, and "Collective Plating" means that the entire conductors are tin plated collectively as shown in <FIG>.

"Pipe" for "Terminal Shape" means that the terminal is in a pipe shape as the terminal <NUM> shown in <FIG>. Also, "Open-Barrel Lapped" refers to the shape shown in <FIG>, "Open-Barrel Zigzag" refers to the shape shown in <FIG>, "Open-Barrel (No digging)" refers to the shape shown in <FIG>, and "Open-Barrel (With digging)" refers to the shape shown in <FIG>.

"Conductor Compression Rate" is the total cross-sectional area of the conductors after compression to the total cross-sectional area of the conductors before compression at the conductor crimp part. Also, "Tension member Compression Rate" is the apparent compression rate of the region of the tension member, and is the cross-sectional area of the region surrounded by the conductive wires after compression to the cross-sectional area of the region surrounded by the conductive wires before compression at the conductor crimp part.

"Crimp part Resistance" is an electric resistance between a front end of the terminal and a rear end of the coated conductive wire of <NUM> length. "Crimp part Resistance" is marked as "Excellent" for the crimp part resistance less than <NUM> mΩ, marked as "Good" for the crimp part resistance between <NUM> mΩ and <NUM> mΩ, and marked as "Bad" for the crimp part resistance more than <NUM> Ω. "Tensile Strength" is a load to pull out the coated conductive wire from the terminal. "Tensile Strength Performance" is marked as "Excellent" for tensile strength of 50N or more, "Good" for tensile strength equal to or more than 40N and less than 50N, and "Bad" for tensile strength of less than 40N. Also, "Anticorrosion Performance" is measured by spraying salt water having a concentration of <NUM> mass% at a temperature of <NUM> at pressure between <NUM> kPa and <NUM> kPa for <NUM> hours, and then leaving at a temperature of <NUM> with humidity between <NUM>% and <NUM>% for <NUM> hours. After that, samples are dried at room temperature to be checked for electrical conductivity, and those have electrical conductivity are marked as "Excellent".

As shown in Table <NUM> to Table <NUM>, both Crimp part Resistance Performance and Tensile Strength Performances are "Good" or "Excellent" in every sample in which tensile strength of the tension member is greater than that of the conductive wire, the tension member is formed of the plurality of strands, and the cross-sectional area of the electric wire is between <NUM> sq and <NUM> sq. In particular, Crimp part Resistance Performance is "Excellent" for all the above cases except in the case in which the conductive wire material is other than Corson alloy wire. Also, Tensile Strength Performance is "Excellent" for all those having the tension member made of resin fiber other than carbon fiber.

On the other hand, Comparison Example <NUM> or <NUM> does not include the tension member and is crimped moderately or strongly. Thus, when being crimped, the conductive wire breaks, which results in "Bad" for Tensile Strength Performance. In contrast, Comparison Example <NUM> is crimped weakly, and thus Tensile Strength Performance is "Excellent". However, an oxide film on the surface of the conductive wire is not destroyed satisfactory, and thus Crimp part Resistance Performance is marked as "Bad".

In Comparison Examples <NUM> and <NUM>, the tension member is single wired and the outer surface of the tension member hardly deforms. Thus, the conductive wire is crashed excessively and breaks at the time of crimping, and Crimp part Resistance Performance is "Bad". On the other hand, in Comparison Example <NUM>, crimping is weaker than in Comparison Examples <NUM> and <NUM>, which suppresses crashing of the conductive wire and resulting "Good" in Crimp part Resistance Performance. However, crimping is insufficient and thus Tensile Strength Performance is "Bad". Similarly in Comparison Example <NUM>, the tension member is single wired and the outer surface hardy deforms. Thus, Crimp part Resistance Performance is "Bad" and, furthermore, copper and stainless wires are in contact with each other and thus Anticorrosion Performance is "Bad" due to electrolytic corrosion between different metals.

Also, in Comparison Example <NUM>, although the tension member is made of resin fiber, tensile strength of the tension member is lower than that of the conductive wire material and thus the tension member is crashed when being crimped, which results in "Bad" in Tensile Strength Performance. Also, in Comparison Example <NUM>, the barrel pieces at the conductive crimp part dig into the tension member, disturbing the arrangement of the conductors, and thus Crimp part Resistance Performance is "Bad". Furthermore, the tension member is also damaged and thus Tensile Strength Performance is also "Bad".

For example, the above descriptions illustrate the examples in which one layer of the conductive wire <NUM> is disposed on the outer periphery of the tension member <NUM>. However, there are various ways of disposing the conductive wire <NUM>. If the conductive wire <NUM> is disposed on a side of the outer periphery side of the tension member <NUM>, two layers of the conductive wire <NUM> may be disposed around the tension member <NUM> as shown in <FIG>, or three layers of the conductive wire <NUM> may be disposed around the tension member <NUM> as shown in <FIG>. Also, the number of the conductive wires <NUM> is at least three for a layer that is in contact with the tension member <NUM>, and is preferably twenty or less, in view of conductivity and strength of the conductive wire <NUM>. For example, the number of the conductive wires <NUM> may be twelve or fourteen as shown in <FIG>, <FIG>, <FIG>, etc. or may be six or eight.

Claim 1:
A terminal-equipped electric wire (<NUM>, 10a) in which a coated conductive wire (<NUM>) and a terminal (<NUM>, 1a) are electrically connected to each other,
wherein the coated conductive wire (<NUM>) comprises:
a tension member (<NUM>) comprising a plurality of strands (17a) so that an unevenness is formed on an outer periphery surface of the tension member (<NUM>); and
a conductive wire (<NUM>) that is disposed on an outer periphery of the tension member (<NUM>) and the conductive wire (<NUM>) is formed of a plurality of conductors,
wherein a cross-sectional area of the conductive wire (<NUM>) is <NUM><NUM> or less; and
wherein a tensile strength of the tension member (<NUM>) is greater than tensile strength of the conductive wire (<NUM>), and
wherein the terminal (<NUM>, 1a) comprises:
a conductive wire crimp part (<NUM>) at which the conductive wire (<NUM>) being exposed from a coating at a tip end of the coated conductive wire (<NUM>) is crimped; and
a coating crimp part (<NUM>) at which the coating of the coated conductive wire (<NUM>) is crimped;
wherein the conductive wire (<NUM>) is crimped at the conductive wire crimp part (<NUM>) from an entire circumference of the circumferential direction of the conductive wire (<NUM>) at a predetermined position in an axial direction; and
wherein the conductive wire (<NUM>) deforms so as to be fitted into the unevenness formed on an outer periphery surface of the tension member (<NUM>) thereby preventing the conductive wire (<NUM>) from being excessively crashed and broken.