Patent Application
20230133056
The present invention relates to a terminal-equipped electric wire and the like that are used in motor vehicles, for example.
A wire harness for motor vehicles is a bundle of coated conductive wires in which a conductor is connected with 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 at the time of crimping the conductive wire crimp part. Thus, strands forming the conductor arc 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 0.35 sq (sq: mm2) 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 30 N, to obtain tensile strength of 80 N or more, which is a requirement for an electric wire for motor vehicles, Patent Document 1 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, Patent Document 2 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.
However, in both Patent Documents 1 and 2, 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 Patent Document 1 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, Patent Document 1 has problems that manufacturing steps are complex and thus processing cost is high.
Also, Patent Document 2 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 Patent Document 2, 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, Patent Document 2, similarly to Patent Document 1, 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 0.35 sq 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 may include a plurality of strands.
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 is crimped at the conductive wire crimp part at a predetermined position in an axial direction from the entire circumference.
Preferably, the conductive wire crimp part is not in contact with the tension member.
The cross-sectional area of the conductive wire may be 0.3 sq 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 conductive wire 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 0.35 sq or less, or as small as 0.3 sq 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 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.
A third aspect of the present invention is a method for manufacturing the terminal-equipped electric wire according to the first aspect of the present invention. The method includes crimping the conductive wire crimp part. Both the compression rate of the conductive wire and the apparent compression rate of the tension member are lowered in an early stage of compression, and by compressing further, reduction in the apparent compression rate of the tension member becomes relatively small while reduction in the compression rate of the conductive wire progresses mainly.
According to the third aspect of the present invention, the coated conductive wire and the terminal can be easily crimped together through the steps that are similar to those used for conventional terminal-equipped electric wires. For example, although both the compression rates of the tension member and the conductive wire are reduced simultaneously at the early stage of the compression, the tension member reaches compression limit first with no further reduction in the compression rate, which may likely to generate a difference between the compression rates of the tension member and the conductive wire. In such crimping where there is a difference in the compression rates, the compression rate of the tension member can be maintained high while it is possible to reduce the compression rate of the conductive wire. Thus, such the crimping is particularly effective for the conductive wire that needs strong crimping to lower the crimp part resistance. Note that even if the compression rates of the tension member and the conductive wire are equal, such the crimping never crashes the tension member excessively and can achieve higher tensile strength than conventional techniques.
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.
The coated conductive wire 11 is formed of a conductive wire 13, which is made of copper, copper alloy metal, aluminum, or aluminum alloy metal, for example, and a coating 15, which coats the conductive wire 13. That is, the coated conductive wire 11 includes the coating 15 and the conductive wire 13 being exposed from a tip end of the coating 15.
The terminal 1 is made of copper, copper alloy metal, aluminum, or aluminum alloy metal, for example. The coated conductive wire 11 is connected to the terminal 1. The terminal 1 is formed of a terminal body 3 and a crimp part 5 that are joined together via a transition part 4.
The terminal body 3 is made by forming a predetermined shaped plate-like material into a tubular body having a rectangular cross section. The terminal body 3 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 3 to be connected. In the descriptions hereinafter, examples in which the terminal body 3 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 3 in the present invention are not particularly limited. For examples, instead of the female-type terminal body 3, 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 5 of the terminal 1 is a part to which the coated conductive wire 11 is crimped. The crimp part 5 includes a conductive wire crimp part 7 that crimps the conductive wire 13 exposing from the coating 15 at a front-end side of the coated conductive wire 11, and a coating crimp part 9 that crimps the coating 15 of the coated conductive wire 11. That is, the conductive wire 13 being exposed by peeling the coating 15 is crimped by the conductive wire crimp part 7, thereby electrically connecting the conductive wire 13 and the terminal 1 with each other. Also, the coating 15 of the coated conductive wire 11 is crimped by the coating crimp part 9 of the terminal 1. In the present embodiment, each of the conductive wire crimp part 7 and the coating crimp part 9 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 7. The serrations formed in this way can easily break an oxide film on a surface of the conductive wire 13, and also can increase a contacting area with the conductive wire 13 at the time of crimping the conductive wire 13.
As shown in
As mentioned above, the conductive wire crimp part 7 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 7, the conductive wire 13 can be crimped by the conductive wire crimp part 7 from the entire 360° circumference thereof. That is, the conductive wire 13 is crimped at the conductive wire crimp part 7 from an entire circumference of a circumferential direction of the conductive wire 13. Thus, an inner surface of the conductive wire crimp part 7 is in contact with the conductive wire 13 over the entire circumference, which can prevent the conductive wire 13 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 13 (a total of cross-sectional areas of the strands) is 0.35 sq or less. That is, the terminal 1 can crimp the conductive wire 13 having the cross-sectional area of 0.35 sq or less. Furthermore, the cross-sectional area of the conductive wire 13 (the total of cross-sectional areas of the strands) is preferably 0.3 sq or less, and, in such the case, it is preferable that the terminal 1 can crimp the conductive wire 13 having the cross-sectional area of 0.3 sq or less. Also, the conductive wire 13 is used together with the tension member 17, and thus the cross-sectional area of the conductive wire 13 may be 0.05 sq or less. Smaller the cross-sectional area of the conductive wire 13 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 13 is preferably 0.01 sq or more, and more preferably 0.03 sq or more.
The tension member 17 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 17 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 17 is greater than tensile strength of the conductive wire 13. 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 13, the tension member 17 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 17 is greater than that of the conductive wire 13, and yield stress (or proof stress) of the tension member is greater than that of the conductive wire 13.
Next, a method for producing the terminal-equipped electric wire 10 will be described.
First, as mentioned above, the coating 15 at the tip end part of the coated conductive wire 11 is peeled off to expose the conductive wire 13 at the tip end part. Next, as shown in
As mentioned above, the tension member 17 is disposed at the substantially center and the conductive wire 13 is disposed on the outer periphery of the tension member 17. The conductive wire 13 is formed of the plurality of strands. In such the case, as shown in
Also, as shown in
Note that, when plating collectively the tip end part of the conductive wire 13 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 13 using such the plating method, the heat may deteriorate the tension member 17, which may lower tensile strength.
In such the case, as shown in
The method for end processing the processed end part 19 is not limited to compression or plating. For example, soldering or welding the tip end of the conductive wire 13 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 11 with the tip end part being processed as above is inserted into the pipe-shaped crimp part 5 of the terminal 1 from the rear-end side thereof. When the tip end part of the coated conductive wire 11 is inserted into the crimp part 5, the exposed part of the conductive wire 13 is positioned inside the conductive wire crimp part 7, and the coating 15 is positioned inside the coating crimp part 9. At this time, the tip end of the conductive wire 13 may come out of a front end of the conductive wire crimp part 7.
In
The cross-sectional area of the conductive wire 13 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 11, 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 13, 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 13 (A in
Here, the compression rate of the conductive wire 13 after crimping is equal to or less than the apparent compression rate of the region on which the tension member 17 is disposed. The compression rate of the conductive wire 13 is A3/A0 (%), wherein A0 refers to the total cross-sectional area of the conductive wire 13 before the crimping process (
As mentioned above, the conductive wire 13 is crimped at the conductive wire crimp part 7 from the entire circumference of the circumferential direction of the conductive wire 13. Also, as shown in
For example, if the tension member 17 is a single wire, the interface between the conductive wire 13 and the tension member 17 is almost flat and smooth. At this time, since the tension member 17 is unlikely to deform compared to the conductive wire 13, the conductive wire 13 deforms being crashed along the surface of the tension member 17. This may cause the conductive wire 13 to become too thin and break. By contrast, if there is unevenness formed on the outer periphery surface of the tension member 17, the conductive wire 13 can deform as to be fitted into such unevenness, and this can prevent the conductive wire 13 from being excessively crashed and broken.
Since an amount of deformation of the tension member 17 (the tension member strands 17a) is small compared to that of the conductive wire 13, fracture of the tension member 17 due to the reduction in the cross-sectional area is unlikely to occur. In particular, the tension member 17 does not suffer damages since the conductive wire crimp part 7 is in a pipe shape and the conductive wire 13 is compressed from the entire periphery, and the conductive member 13 is disposed between the tension member 17 and the conductive wire crimp part 7 and the tension member 17 and the conductive wire crimp part 7 are not in contact with each other.
As shown in
Accordingly, the terminal-equipped electric wire 10 can be obtained. Furthermore, a wire harness in which a plurality of terminal-equipped electric wires, including the terminal-equipped electric wire 10 obtained as above, are unified together as one body can be obtained.
As described above, according to the present embodiment, the conductive wire 13 is crimped at the conductive wire crimp part 7 from the entire 360° circumference, and this can prevent local stress (deformation) applied to the conductive wire 13 at the time of crimping. It is also possible to perform the crimping without greatly altering the structure in which the tension member 17 is disposed in the middle and the conductive wire 13 is twisted around the tension member 17. Also, since the conductive wire crimp part 7 is in contact with the entire circumference of the conductive wire 13, deterioration in resistance can be prevented.
Also, since tensile strength of the tension member 17 is greater than that of the conductive member 13, further stronger crimping can be performed. That is, the strong crimping does not damage the tension member 17, and this can prevent fracture of the coated conductive wire 11 at the conductive wire crimp part 7. Also, with the strong crimping, the oxide film of the conductive wire 13 can be broken and thus the conductive wire 13 and the terminal 1 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 0.35 sq or less.
Also, since the tension member 17 is formed of the tension member strands 17a, in the early stages of crimping, deformation of the conductive wire 13 and deformation by reducing the spaces between the tension member strands 17a progress. Thus, compression force is not applied only to the conductive wire 13 and the conductive wire 13 is moderately deformed by compression. Also, unevenness is formed on the outer periphery surface of the tension member 17 and the conductive wire 13 deforms being fitted along the unevenness shape, which prevents excessive crashing of the conductive wire 13.
At the conductive wire crimp part 7, the terminal 1 (the conductive wire crimp part 7) is crimped to the conductive wire 13 inside, and the conductive wire 13 is crimped to the tension member 17 (the tension member strands 17a) inside. At this time, if there is a sufficient amount of compression in the conductive wire crimp part 7, frictional force between the terminal 1 (the conductive wire crimp part 7) and the conductive wire 13 and frictional force between the conductive wire 13 and the tension member 17 (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 1 (the conductive wire crimp part 7) and the conductive wire 13, it is difficult to achieve the sufficient frictional force between the conductive wire 13 and the tension member 17 (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 7 within a scope that the conductive wire 13 does not break.
Furthermore, in a case, like the present embodiment, in which the conductive wire crimp part 7 is in a tubular shape having the joint part being brazed, the compression stress onto the conductive wire 13 is small at the brazed part where hardness is low and thus the tension member 17 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 7 preferably has no brazed part and has the same hardness as the material used for the conductive wire crimp part 7.
Next, a second embodiment will be described.
The terminal 1a has approximately the same configuration as the terminal 1 except that the crimp part 5 is an open-barrel type. The terminal 1a can be crimped similarly as the terminal 1.
Here, at the open-barrel type conductive wire crimp part 7, at least a pair of facing barrel pieces are folded to crimp the conductive wire 13. 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 7. At the coating crimp part 9, facing barrel pieces may be butted against each other, or, similarly to the conductive wire crimp part 7, 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 13 over the entire circumference.
However, even in such the case, the gaps 23 are not aligned along the axial direction of the conductive wire crimp part 7 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 13 is always crimped over the entire circumference of the circumferential direction at some positions of the axial direction of the conductive wire crimp part 7. For example, the position of the circumferential direction of the gap 23 in
As above, the same effects as in the first embodiment etc. can be obtained if the crimp part 5 at the conductive wire crimp part 7 is an open-barrel type. In addition, with the open-barrel type crimp part 5, disposing the conductive wire 13 onto the crimp part 5 is easy.
As above, if it is possible to make certain that the conductive wire 13 is compressed from the entire circumference at the conductive wire crimp part 7, the conductive wire crimp part 7 may be in a shape other than a pipe shape. Also, with the open-barrel type conductive wire crimp part 7, 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 7.
For example,
Also, as shown in
Various types of terminal-equipped electric wires are produced, and electrical properties (electric 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 1, and conditions and results of the evaluation are shown in Table 2 to Table 10.
“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
“Pipe” for “Terminal Shape” means that the terminal is in a pipe shape as the terminal 1 shown in
“Conductor Compression Rate” is the total cross-sectional area of the conductors after crimping to the total cross-sectional area of the conductors before crimping at the conductive wire 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 crimping to the cross-sectional area of the region surrounded by the conductive wires before crimping at the conductive wire 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 100 mm length. “Crimp Part Resistance” is marked as “Excellent” for the resistance less than 1 mΩ, marked as “Good” for the resistance between 1 mΩ and 2 mΩ, and marked as “Bad” for the resistance more than 2 mΩ. “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 5 mass % at a temperature of 35° C. at pressure between 68.6 kPa and 176.5 kPa for 96 hours, and then leaving at a temperature of 80° C. with humidity between 90% and 95% for 96 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 2 to Table 8, both the crimp part resistance 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 0.05 sq and 0.35 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 1 or 3 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 2 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 4 and 5, 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 6, crimping is weaker than in Comparison Examples 4 and 5, 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 7, 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 8, 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 9, 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”.
Although the embodiments of the present invention have been described referring to the attached drawings, the technical scope of the present invention is not limited to the embodiments described above. It is obvious that persons skilled in the art can think out various examples of changes or modifications within the scope of the technical idea disclosed in the claims, and it will be understood that they naturally belong to the technical scope of the present invention.
For example, the above descriptions illustrate the examples in which one layer of the conductive wire 13 is disposed on the outer periphery of the tension member 17. However, there are various ways of disposing the conductive wire 13. If the conductive wire 13 is disposed on a side of the outer periphery of the tension member 17, two layers of the conductive wire 13 may be disposed around the tension member 17 as shown in
Also, in the descriptions above, examples in which the tension member 17 is formed of the plurality of strands 17a are described. However, the tension member 17 may be single wired if the outer shape of the tension member 17 can deform with the conductive wire 13 at the time of crimping and there are uneven shapes formed on the outer periphery thereof after compression. For example, in the above Comparison Examples 4 to 7, although the tension member is single wired and failed the evaluation, it is possible to suppress deterioration of Crimp Part Resistance Performance if the outer surface of the tension member can deform slightly. However, the tension member 17 does not function as a tension member if the tension member 17 is more deformable than the conductive wire 13. Thus, at the time of crimping, it is preferable that there is small unevenness formed on the surface of the tension member due to pressure from the conductive wire 13 when the conductive wire 13 primarily crashes and extends in the axial direction.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-117111 | Jul 2020 | JP | national |
| 2020-196035 | Nov 2020 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2021/025453 | Jul 2021 | US |
| Child | 18148721 | US |
