Electric wire with terminal, wiring harness, and manufacturing method of electric wire with terminal

Abstract

To provide an electric wire with terminal or the like capable of achieving both of a connection strength and a connection resistance.SOLUTION: An electric wire 10 with terminal is constructed so that a coated wire 11 is crimped to a terminal 1, and is electrically connected. A dimension A (mm) of a longer direction of a conducting wire compression part 7 is set so as to satisfy a condition of 4≤(A*B*C*D) / E≤20 where a total peripheral length of a conducting wire 13 before a crimp exposed to an outer periphery when a coated part 15 is removed is B (mm); a tension strength of the conducting wire 13 is C(MPa); a ratio of a dimension in a peripheral direction of the conducting wire 13 of the conducting wire compression part 7 in the sate where the conducting wire compression part 7 is crimped to the conducting wire 13 and a peripheral length of the conducting wire 13 (the peripheral length of the conducting wire 13 coated by the conducting wire compression part 7 after crimping / a whole peripheral length of the conducting wire 13 in the conducting wire compression part 7 after crimping) is D, and a connection strength of the conducting wire compression part 7 and the conducting wire 13 is E(N).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric wire with a terminal for use in, for example, an automobile. [Background technology]

[0002] Typically, automotive wire harnesses are made by connecting crimp terminals to the conductors of covered conductors, bundling them together, and wiring them as signal wires for automobiles, etc. A typical covered conductor and crimp terminal are connected by removing the coating from the tip of the covered conductor, crimping the exposed conductor with the conductor crimping portion, and crimping the coating with the coating crimping portion. Automotive wire harnesses satisfy the connection strength requirements between the crimp terminal and the covered conductor by the combined connection strength of the conductor crimping portion and the coating crimping portion.

[0003] As the conductor crimping portion, for example, a so-called open barrel type in which a pair of barrel pieces are bent and crimped so as to bite into the conductor, and a cylindrical crimping portion in which a conductor is inserted into a cylindrically formed conductor crimping portion and crimped, making it possible to seal the crimping portion, have been proposed (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-89834 [Patent Document 2] JP 2016-46171 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, particularly in the automotive field, the number of ECUs and sensors has increased in response to CASE and other trends, and the number of electric wires used has increased significantly. In this situation, increasing the wire diameter of wire harnesses has become an issue. For this reason, there is a demand for further thinning of automotive electric wires. For example,2 There is a demand for thin wires with a diameter of less than 100 mm.

[0006] Thus, when crimping particularly thin electric wires, for example, in a general open barrel type terminal as in Patent Document 1, strong crimping is usually required to increase the connection strength and decrease the connection resistance. For this reason, the tip of the barrel piece bites into the conductor wire strongly, which may cause the wires constituting the conductor wire to come apart or break, which is a factor of decreasing the connection strength and worsening the electrical resistance. In addition, there is a method of using a coated conductor wire having a tensile strength wire inside to improve the connection strength, but even in this case, the tip of the barrel piece bites into the conductor wire, so the conductor and the tensile strength wire are not crimped together, which is a factor of decreasing the connection strength, etc.

[0007] On the other hand, in a method of crimping a conductor wire from the entire circumference in a substantially circular shape, such as a cylindrical terminal as in Patent Document 2, biting like that of the open barrel type is suppressed, but if the conductor wire is strongly crimped to increase the connection strength and reduce the connection resistance, the elongation of the internal conductor wire and the crimped part of the terminal will not be uniform in the circumferential direction, and there is a concern that the connection strength may actually decrease. However, if the crimping is weak, sufficient connection strength may not be obtained and the connection resistance may also increase.

[0008] The present invention has been made in view of the above problems, and has an object to provide an electric wire with a terminal or the like that is capable of achieving both connection strength and connection resistance. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, a first invention is an electric wire with terminal in which a covered conductor wire is crimped to a terminal, the covered conductor wire being a strength member and a conductor wire that are covered by a covering portion, the terminal being equipped with a crimping portion to which the conductor wire exposed from the covering portion at the tip of the covered conductor wire is crimped, the conductor wire is composed of a wire that is arranged on the outer periphery of the tensile member, and the electric wire with terminal is characterized in that, when A (mm) is the longitudinal dimension of the conductor wire crimped at the crimping portion, B (mm) is the total circumferential length of the conductor wire before crimping that is exposed on the outer periphery when the covering portion is removed, C (MPa) is the tensile strength of the conductor wire, D is the ratio of the circumferential dimension of the crimping portion when the crimping portion is crimped to the conductor wire to the overall circumferential length of the conductor wire, and E (N) is the connection strength between the crimping portion and the conductor wire, the electric wire with terminal satisfies the condition 4≦(A×B×C×D) / E≦20.

[0010] It is desirable for the cross-sectional area of ​​the wire to be 0.35 sq. or less.

[0011] The conductive wire may be arranged in plurality on the outer periphery of the tension member.

[0012] According to the first invention, by setting appropriate conditions including the length of the conductor crimping portion and the circumference of the conductor, even a thin conductor can be crimped while achieving both connection strength and connection resistance.

[0013] This effect is particularly effective when the cross-sectional area of ​​the electric wire is small, ie, 0.35 sq. or less.

[0014] Furthermore, by arranging a plurality of conductors on the outer periphery of the tension member, a higher connection strength can be obtained.

[0015] The second invention is a wire harness characterized in that a plurality of electric wires with terminals, including the electric wire with terminal according to the first invention, are bundled together. In this way, a plurality of electric wires with terminals can be bundled together for use.

[0016] A third invention is a method for manufacturing an electric wire with terminal, the terminal being of an open barrel type and having at least a crimping portion capable of crimping a conductor, ends of barrel pieces of the crimping portion are rolled without being joined together, a conductor exposed from a tip of a coating portion of a coated conductor is inserted into the approximately cylindrical crimping portion, and the conductor is crimped by the crimping portion, wherein a longitudinal dimension of the crimping portion is A (mm), a total circumferential length of the conductor before crimping that is exposed on the outer periphery when the coating is removed is B (mm), a tensile strength of the conductor is C (MPa), a ratio of a circumferential dimension of the crimping portion in a state in which the crimping portion is crimped to the conductor to the overall circumferential length of the conductor is D, and a connection strength between the crimping portion and the conductor is E (N), the method for manufacturing an electric wire with terminal is characterized in that: 4≦(A×B×C×D) / E≦20 is satisfied.

[0017] Also, there may be provided a method for manufacturing an electric wire with a terminal, the method being characterized in that the terminal has at least a crimping portion capable of crimping a conductor, ends of barrel pieces of the crimping portion are rounded, a conductor exposed from a tip of a coating portion of a coated conductor is inserted into the approximately cylindrical crimping portion and crimped with the crimping portion, a longitudinal dimension of the crimping portion is A (mm), a total circumferential length of the conductor before crimping that is exposed on the outer periphery when the coating portion is removed is B (mm), a tensile strength of the conductor is C (MPa), a ratio of a circumferential dimension of the crimping portion in a state in which the crimping portion is crimped to the conductor to an overall circumferential length of the conductor is D, and a connection strength between the crimping portion and the conductor is E (N), the method being characterized in that the following condition is satisfied: 4≦(A×B×C×D) / E≦20.

[0018] According to the third invention, instead of crimping the conductor by bending the barrel pieces as in a conventional open barrel type, the conductor crimping portion is formed by rolling it into a cylindrical shape in advance, and the conductor is crimped while still in a roughly cylindrical shape, so that the barrel pieces do not bite into the conductor. Effect of the Invention

[0019] According to the present invention, it is possible to provide an electric wire with a terminal that is capable of achieving both connection strength and connection resistance. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a perspective view showing a terminal-fitted electric wire 10. [Diagram 2] 2(a) to 2(c) are cross-sectional views showing an electric wire 10 with a terminal. [Diagram 3] FIG. [Figure 4] FIG. 4 is a radial cross-sectional view of the conductor 13 other than the crimped portion. [Diagram 5] FIG. 4 is a radial cross-sectional view showing the conductor crimping portion 7. [Figure 6] FIG. [Figure 7] FIG. 2 is a perspective view showing the terminal 1 and the covered conductor wire 11 before crimping. [Figure 8] FIG. 11 is an axial cross-sectional view of another conductor crimping portion 7. [Figure 9] FIG. 2 is a perspective view showing a terminal 1a before crimping. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an electric wire with terminal 10, and Fig. 2(a) is a cross-sectional view of a conductor crimping portion 7. The electric wire with terminal 10 is configured by crimping a covered conductor wire 11 to a terminal 1 and electrically connecting them.

[0022] The covered conductor wire 11 is composed of a strength member 17, a conductor wire 13, and a covering 15 that covers the conductor wire 13. In this embodiment, the conductor wire 13 is composed of a plurality of strands that are arranged on the outer periphery of the strength member 17, and the strands are twisted together. That is, in the covered conductor wire 11, the strength member 17 and the conductor wire 13 are covered with the covering 15, and the conductor wire 13 is exposed from the tip.

[0023] Conductive wire 13 is made of, for example, copper, copper alloy, aluminum or aluminum alloy, silver, or magnesium. More specifically, applicable copper and copper alloys include oxygen-free copper, tough pitch copper, brass, Cu-Sn alloy, Corson copper, etc., and applicable aluminum and aluminum alloys include pure aluminum, Al-Cu, Al-Fe, Al-Mg-Si, etc. More preferably, when the diameter (nominal cross-sectional area) of conductive wire 13 is 0.35 sq or less, a Cu-0.7 mass% Sn alloy is preferable, and when the diameter (nominal cross-sectional area) exceeds 0.35 sq, tough pitch copper is preferable.

[0024] Examples of the tensile member 17 that can be used include aramid fibers (e.g., Kevlar (registered trademark) 29 (tensile strength 2920 MPa) manufactured by DuPont-Toray Co., Ltd.), PBO fibers (e.g., Zylon (registered trademark) AS (tensile strength 5800 MPa) manufactured by Toyobo MC Co., Ltd.), polyarylate fibers (e.g., Vectran (registered trademark) UM (tensile strength 2840 MPa) manufactured by Kuraray Co., Ltd.), carbon fibers (e.g., PYROFIL (registered trademark) TR 30S 3L (tensile strength 4120 MPa) manufactured by Mitsubishi Chemical Corporation), glass fibers, and the like.

[0025] A coated conductor wire 11 is connected to the terminal 1. The terminal 1 is configured by connecting a terminal body 3 and a crimping portion 5 via a transition portion 4. The terminal 1 is made of, for example, copper, a copper alloy, aluminum, an aluminum alloy, or the like, and may be made of, for example, the same material as that of the conductor wire 13. When the terminal 1 is made of copper (copper alloy), Sn plating or the like may be provided.

[0026] The terminal body 3 is a plate-like member of a predetermined shape formed into a cylindrical body with a rectangular cross section. The terminal body 3 has an elastic contact piece formed by folding the plate-like member into the rectangular cylindrical body inside. The terminal body 3 is connected by inserting a male terminal or the like from the front end. In the following description, an example is shown in which the terminal body 3 is a female terminal that allows the insertion of an insertion tab (not shown) of a male terminal or the like, but the detailed shape of the terminal body 3 is not particularly limited in the present invention. For example, an insertion tab of a male terminal may be provided instead of the female terminal body 3, or a bolt fastening portion like a round terminal may be provided.

[0027] The crimping portion 5 of the terminal 1 is a portion that is crimped to the covered conductor wire 11, and includes a conductor crimping portion 7 that crimps the conductor wire 13 exposed from the coating portion 15 at the tip side of the covered conductor wire 11, and a coating crimping portion 9 that crimps the coating portion 15 of the covered conductor wire 11. That is, the conductor wire 13 exposed when the coating portion 15 is peeled off is crimped by the conductor crimping portion 7, and the conductor wire 13 and the terminal 1 are electrically connected. Also, the coating portion 15 of the covered conductor wire 11 is crimped by the coating crimping portion 9 of the terminal 1.

[0028] Serrations (not shown) may be provided in a portion of the inner surface of the conductor crimping portion 7 in the width direction (direction perpendicular to the longitudinal direction). By forming serrations in this manner, the oxide film on the surface of the conductor 13 is easily broken when the conductor 13 is crimped, and the contact area with the conductor 13 can be increased. In the case of a thin-diameter electric wire, since there is a risk of breakage due to the steps of the serrations, the inner surface of the conductor crimping portion may be roughened to form fine irregularities on the surface.

[0029] As shown in Fig. 2(a), the conductor crimping portion 7 is formed into a generally cylindrical shape by rolling a barrel piece, which is a plate-like member. The butt joints 23 of the barrel pieces are not joined by welding or the like over their entire length. In the conductor crimping portion 7, the conductor 13 is crimped into a generally cylindrical shape from approximately the entire circumference.

[0030] The shape of the conductor crimping portion 7 after crimping is preferably substantially circular. Here, the substantially circular shape of the conductor crimping portion 7 includes a somewhat flattened shape (substantially elliptical shape) as shown in Fig. 2(a) and also includes a case where a slight protrusion is formed on the outer periphery of the portion corresponding to the mating portion of the mold.

[0031] In this way, the conductor crimping portion 7 to which the conductor 13 is crimped is preferably such that the conductor 13 is compressed almost uniformly from the entire circumference, and the butt joints 23 of the ends of the opposing barrel pieces are butted together without being bent toward the conductor 13. In other words, it is preferable that the cross section of the conductor crimping portion 7 is substantially circular, and the conductor crimping portion 7 is compressed so as to reduce its diameter overall. As shown in FIG. 2(b), the substantially circular conductor crimping portion after crimping may have the butt joints 23 of the barrel pieces slightly bent toward the center. Also, as shown in FIG. 2(c), the ends of the barrel pieces of the conductor crimping portion 7 may be formed to overlap each other after crimping.

[0032] However, as shown in Fig. 2(b), if the tip of the barrel piece is bent onto the outer surface of the conductor 13, there is a risk of breakage if the conductor 13 is thin, so it is more preferable that the barrel pieces are crimped together so as not to bite into the conductor 13. Furthermore, as shown in Fig. 2(c), if the barrel pieces overlap, a rotational force is applied to the conductor 13 during crimping, so it is preferable that the barrel pieces are butted together at butt joint 23 without overlapping.

[0033] Here, the cross-sectional area (nominal cross-sectional area) of the conductor 13 including the tensile member 17 may be more than 0.35 sq., but this embodiment is particularly effective when it is 0.35 sq. or less. Furthermore, the conductor 13 may be 0.3 sq. or less, or 0.13 sq. or less, and the smaller the diameter of the conductor 13, the more effective it is. On the other hand, when the cross-sectional area of ​​the conductor 13 is small, crimp connection tends to become difficult, so the cross-sectional area of ​​the conductor 13 is preferably 0.01 sq. or more, and more preferably 0.03 sq. or more.

[0034] In this embodiment, in consideration of the fact that the connection strength per unit length of conductor 13 at which conductor 13 can be crimped without breaking decreases as the diameter of conductor 13 decreases, the connection strength is ensured by increasing the length of conductor crimping portion 7. Fig. 3 is an axial cross-sectional view of conductor crimping portion 7. The longitudinal dimension A (mm) of the conductor crimping portion 7 is set to satisfy the condition 4≦(A×B×C×D) / E≦20, where B (mm) is the total circumference of the conductor 13 before crimping that is exposed on the outer periphery when the covering portion 15 is removed, C (MPa) is the tensile strength of the conductor 13, D is the ratio of the circumferential dimension of the conductor crimping portion 7 in the state where the conductor crimping portion 7 is crimped to the conductor 13 to the circumference of the conductor 13 (circumference of the conductor 13 covered by the conductor crimping portion 7 after crimping / total circumference of the conductor 13 at the conductor crimping portion 7 after crimping), and E (N) is the connection strength between the conductor crimping portion 7 and the conductor 13.

[0035] For example, the length A of the conductor crimping portion 7 is desirably 2 mm or more, and more desirably 3 mm or more. In this case, for example, in the case of an electric wire of 0.35 sq or less, the length A of the conductor crimping portion is desirably 5 times or more the outer diameter of the conductor 13, and further, in the case of 0.13 sq or less, the length A of the conductor crimping portion is desirably 8 times or more the outer diameter of the conductor 13, and further, in the case of 0.08 sq or less, the length A of the conductor crimping portion is desirably 10 times or more the outer diameter of the conductor 13.

[0036] FIG. 4(a) is a cross-sectional view of the conductor 13 at a portion other than the crimped portion 5. That is, it is a cross-sectional view of the conductor 13 before crimping. As described above, the conductor 13 has a plurality of strands arranged on the outer periphery of the tensile member 17. Here, the "total circumferential length B of the conductor 13 before crimping that is exposed on the outer periphery when the covering portion 15 is removed" is the solid line B shown in FIG. 4(b). That is, it is considered that 1 / 2 of the circumferential length of each strand is exposed on the outer periphery, and therefore, it is calculated by (strand diameter x π / 2) x number of strands. Note that, when strands are arranged in two or more layers on the outer periphery of the tensile member 17, it is calculated by the number of strands in the outermost layer.

[0037] 5 is a radial cross-sectional view of the conductor crimping portion 7. The ends of the butted portion 23 do not necessarily need to be in complete contact with each other. For example, a gap equal to or smaller than the diameter of the wire may be formed. Even in this case, the conductor crimping portion 7 is assumed to be substantially cylindrical. Here, the "ratio D of the dimension of the conductor crimping portion 7 in the circumferential direction of the conductor 13 when the conductor crimping portion 7 is crimped to the conductor 13 to the circumferential length of the conductor 13" refers to the ratio of the circumferential length (FIG. F) of the range in which the conductor crimping portion 7 covers the conductor 13 to the entire circumferential length of the conductor 13 (if the conductor crimping portion is circular, the inner diameter of the conductor crimping portion after crimping ×π). D=1 indicates that there is no gap at the butted portion 23 and the entire periphery of the conductor 13 is covered by the conductor crimping portion 7.

[0038] In addition, "the connection strength E (N) between the conductor crimping portion 7 and the conductor 13" corresponds to the tensile strength defined by the Japanese Industrial Standard "JIS C 5402-16-4:2012 Connectors for electronic equipment - Tests and measurements - Part 16-4: Mechanical tests on contacts and terminations - Test 16d: Tensile strength (crimp connection)".

[0039] In this way, when the diameter of the conductor 13 is reduced, the contact area between the conductor 13 and the conductor crimping portion 7 in the length direction can be secured, thereby increasing the connection strength. That is, in the past, it was common technical knowledge that when the diameter of the conductor 13 is reduced, the overall size of the conductor crimping portion 7 is correspondingly reduced, but in this embodiment, in order to prevent breakage of the conductor 13 during crimping due to application of a force to the conductor crimping portion 7 that the conductor 13 cannot withstand, the length of the conductor crimping portion is increased as the diameter becomes smaller, thereby ensuring the connection strength.

[0040] Furthermore, if the total circumferential length of the conductor 13 exposed at the outer periphery is increased, it is possible to obtain the same effect as increasing the length of the conductor crimping portion 7. That is, by increasing the total circumferential length of the conductor 13, it is possible to increase the contact area with the conductor crimping portion 7, thereby reducing the connection resistance and increasing the connection strength.

[0041] If (A×B×C×D) / E>20, for example, when conductors of the same diameter and material are crimped under the same conditions (compression rate, connection strength) (i.e., B to E are constant), it is conceivable that the conductor crimping portion 7 will be longer than necessary, making it difficult to apply force evenly to the conductor crimping portion 7, or that the force applied per unit length of the conductor crimping portion 7 will be too small to obtain the required connection strength. In this case, there is a concern that this may have adverse effects such as a decrease in connection strength (specifically, the terminal may come loose during testing after crimping).

[0042] Next, a method for manufacturing the electric wire with terminal 10 will be described. Fig. 6 is a perspective view showing the terminal 1 before crimping. In this embodiment, a normal open barrel type terminal having a conductor crimping portion 7 and a coating crimping portion 9 can be used. That is, in the terminal 1 before processing, the conductor crimping portion 7 and the coating crimping portion 9 each consist of a pair of barrel pieces.

[0043] In the present invention, for the terminal shown in Fig. 6, before crimping, as shown in Fig. 7, the ends of the barrel pieces (plate-like members) of the conductor crimping portion 7 are butted together and rolled to form a tube with a substantially circular cross section, thereby forming the conductor crimping portion 7. At this time, butt joints 23 between the ends of the opposing barrel pieces are not joined by welding or the like. Note that the butt joints 23 may be in contact with each other with no gap, but a gap (smaller than the wire diameter) that does not allow the wire to protrude may be formed due to springback or the like during processing.

[0044] In this way, butt portion 23 is formed substantially straight over the entire length in the axial direction of conductor crimping portion 7. Moreover, no irregularities or changes in cross-sectional shape are formed on the inner and outer surfaces of conductor crimping portion 7, other than butt portion 23. Moreover, it is preferable to leave the open barrel shape of insulation crimping portion 9 as it is, in order to ensure ease of insertion of conductor 13.

[0045] The covering 15 at the tip of the covered conductor wire 11 is stripped in advance to expose the conductor wire 13 at the tip. Next, the conductor wire 13 exposed from the tip of the covering 15 of the covered conductor wire 11 is inserted into the approximately cylindrical conductor crimping portion 7. When the tip of the covered conductor wire 11 is placed in the crimping portion 5, the exposed portion of the conductor wire 13 is located at the conductor crimping portion 7, and the covering 15 is located at the covering crimping portion 9. At this time, the tip of the conductor wire 13 may protrude from the tip of the conductor crimping portion 7.

[0046] Thereafter, the conductor 13 is crimped substantially all around into a substantially cylindrical shape by the conductor crimping section 7, and the covering section 15 is crimped by the covering crimping section 9, thereby obtaining an electric wire with terminal 10 in which the covered conductor 11 and the terminal 1 are electrically connected. Note that the compression ratio in the conductor crimping section 7 (=cross-sectional area of ​​the conductor 13 after compression (total cross-sectional area including the tensile strength member) / cross-sectional area of ​​the conductor 13 before compression (total cross-sectional area including the tensile strength member)) is preferably about 80% to 90%. This is because strong compression may cause breakage of the element wire, particularly in the case of a thin-diameter electric wire. Furthermore, a wire harness in which a plurality of electric wires with terminals, including the obtained electric wire with terminal 10, are bundled and integrated can be obtained.

[0047] In the terminal 1, the conductor crimping portion 7 crimps only the conductor 13, and the covering crimping portion 9 crimps only the covering portion 15, but this is not limited thereto. For example, as shown in FIG. 8, a part of the covering portion 15 may be crimped together with the conductor 13 at the rear end of the conductor crimping portion 7. As described above, in this embodiment, the compression ratio is not so small, so that the covering portion 15 is unlikely to break even when it is crimped. In this case, the Shore hardness (D scale) of the resin used for the covering portion 15 can be appropriately selected within a range of 20 or more and 80 or less (the lower limit is preferably 30 or more, more preferably 40 or more, and the upper limit is preferably 65 or less, more preferably less than 55) according to the intended use of the electric wire with terminal 10. For example, nylon, elastomer, fluororesin, polyvinyl chloride, polyolefin (polyethylene, polypropylene, etc.), ethylene-vinyl acetate copolymer (EVA), etc. can be selected.

[0048] In this way, since the covering portion 15 is weakly crimped at the conductor crimping portion 7, the insertion into the connector is good even if a soft resin is used for the covering portion 15. Also, since the covering portion 15 is crimped together with the conductor 13, it is not necessary to provide the covering crimping portion 9. Therefore, even if the overall length of the conductor crimping portion 7 is increased, the entire crimping portion can be shortened by the gap between the conductor crimping portion 7 and the covering crimping portion 9 and the covering crimping portion 9.

[0049] In the above example, the open barrel type terminal is formed and then formed into a generally cylindrical shape, but instead of additional processing on the terminal 1, the conductor crimping portion 7 may be formed into a cylindrical shape at the same time as forming the terminal 1 from a flat plate-like material. Also, for an open barrel type terminal, the barrel pieces may be rounded at the same time as crimping. That is, forming the generally cylindrical shape and crimping may be performed simultaneously. Also, instead of rounding the barrel pieces during crimping, a terminal in which the barrel pieces have been rounded into a generally cylindrical shape in advance may be used for crimping.

[0050] When the conductor crimping portion 7 is formed in advance into a cylindrical shape, for example, a terminal 1a as shown in FIG. 9 may be used. The terminal 1a is substantially the same as the terminal 1, but sealing portions 25a, 25b are formed at the top and tip of the conductor crimping portion 7. The sealing portions 25a, 25b are completely sealed, for example, by laser welding. That is, the conductor crimping portion 7 is open only at the rear. In addition, an open barrel type insulation crimping portion 9 is provided behind the conductor crimping portion 7.

[0051] A terminal-attached electric wire can be manufactured by inserting the conductor 13 exposed from the coating 15 from the rear of the conductor crimping portion 7, compressing it from the entire circumference, and crimping the coating 15 with the coating crimping portion 9. In this way, the terminal is not limited to an open barrel type terminal, and may be a conductor crimping portion having a closed space. Note that in the case of the terminal 1a, the coating crimping portion 9 may be omitted if the conductor 13 and the tip of the coating 15 can be crimped by the conductor crimping portion 7.

[0052] As described above, according to this embodiment, particularly for a thin diameter conductor 13, when the longitudinal dimension of the conductor crimping portion 7 is A (mm), the total circumferential length of the conductor 13 exposed on the outer periphery is B (mm), the tensile strength of the conductor 13 is C (MPa), the ratio of the circumferential dimension of the conductor crimping portion 7 in the state where the conductor crimping portion 7 is crimped to the conductor 13 to the circumferential length of the conductor 13 is D, and the connection strength between the conductor crimping portion 7 and the conductor 13 is E (N), it is possible to achieve both connection strength and connection resistance by satisfying the condition 4≦(A×B×C×D) / E≦20.

[0053] Furthermore, by rolling the conductor crimping portion 7 into a generally cylindrical shape before inserting the conductor 13, deformation of the conductor crimping portion 7 during crimping can be suppressed, and the conductor crimping portion 7 can be crimped into a generally circular shape. This makes it possible to suppress the barrel pieces from biting into the conductor 13. EXAMPLES

[0054] The connection strength was evaluated by crimping wires of different total conductor circumferences (B) and materials (C) to various terminals with different lengths of conductor crimping part (A). In all cases, the entire conductor crimping part was compressed, and the conductor crimping part of the terminal was crimped to cover 95% of the conductor circumference (D=0.95).

[0055] Here, when the diameter of the conductor is 0.35sq or less, a Cu-0.7 mass% Sn alloy (Sn0.7-Cu) is used, and when it is over 0.35sq, tough pitch copper (TPC) is used. The tensile strength of the Cu-0.7 mass% Sn alloy is 720MPa, and the tensile strength of the tough pitch copper is 300MPa. The material of the terminal is a Cu-Ni-Si copper alloy, and here, "FAS-680" manufactured by Furukawa Electric Co., Ltd. is used.

[0056] For each diameter of conductor, the terminals were crimped under the conditions that would give the following connection strength (E) after crimping: The load during crimping was adjusted to a condition that would give the connection strength (E) after crimping of 1 to 1.2 times the following value, and 20 samples were created under these conditions. 0.05sq~0.35sq:50N 0.75sq:80N 1.25sq:100N 2.5sq:150N 4.8sq:200N

[0057] The specifications of each electric wire are shown in Table 1, the calculation results of (A×B×C×D) / E under each condition are shown in Table 2, and the evaluation results are shown in Table 3.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] In Table 3, × indicates that the conductor wire could not withstand the force applied during crimping and broke during crimping (the load during crimping could not be set to conditions allowing crimping with the specified connection strength), △ indicates that crimping was successful but the terminals of some samples came loose during testing after crimping (the load during crimping could be set to conditions allowing crimping with the specified connection strength but the crimping was unstable), and ◯ indicates that the connection strength was within the above range and was sufficient (the load during crimping could be set to conditions allowing crimping with the specified connection strength and the crimping was stable).

[0062] The results show that good connection strength could be obtained under the specified conditions. Note that the conductor crimped portion length here refers to the length of the portion that is actually crimped to the conductor, and does not mean the entire conductor crimped portion (total length), which is a component of the terminal. In other words, although we will not go into the results here, it is not necessary to compress the entire conductor crimped portion (total length), and the same tendency was observed in this case as well. Furthermore, the connection resistance of all the terminal-attached wires that were able to achieve good connection strength was good.

[0063] Although the embodiment of the present invention has been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art can think of various modifications or alterations within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention. [Explanation of symbols]

[0064] 1, 1a………Terminal 3: Terminal body 4. Transition section 5……… Crimping section 7………Conductor crimping section 9……Sheathing crimping part 10...Terminal wire 11....Coated conductor 13……Conducting wire 15....Coating part 17……Tensile strength body 23...Butt joint 25a, 25b……Sealing part

Claims

1. A terminal-attached electric wire in which a coated conductor wire is crimped to a terminal, The coated conductor wire has a tensile member and a conductor wire coated with a coating portion, the terminal includes a crimping portion to which the conductor exposed from the coating at the tip of the coated conductor is crimped; an electric wire with a terminal, characterized in that the condition of 4≦(A×B×C×D) / E≦20 is satisfied, where A (mm) is the longitudinal dimension of the conductor crimped at the crimping portion, B (mm) is the total circumferential length of the conductor before crimping that is exposed on the outer periphery when the covering portion is removed, C (MPa) is the tensile strength of the conductor, D is the ratio of the circumferential dimension of the crimping portion in a state in which the crimping portion is crimped to the conductor to the overall circumferential length of the conductor, and E (N) is the connection strength between the crimping portion and the conductor.

2. 2. The electric wire with terminal according to claim 1, wherein the cross-sectional area of ​​the electric wire is 0.35 sq. or less.

3. 2. The electric wire with terminal according to claim 1, wherein the conductor comprises a wire disposed on an outer periphery of the tension member.

4. A wire harness comprising a bundle of a plurality of electric wires with terminals including the electric wire with terminal according to claim 1.

5. A method for manufacturing an electric wire with a terminal, comprising the steps of: The terminal is an open barrel type and has at least a crimping portion capable of crimping a conductor wire, The ends of the barrel pieces of the crimping portion are rolled without being joined together, a conductor exposed from a tip of a coating portion of a coated conductor is inserted into the substantially cylindrical crimping portion, and the conductor is crimped by the crimping portion; A method for manufacturing an electric wire with a terminal, characterized in that the condition of 4≦(A×B×C×D) / E≦20 is satisfied, where A (mm) is the longitudinal dimension of the crimping portion, B (mm) is the total circumferential length of the conductor exposed on the outer periphery when the covering portion is removed, C (MPa) is the tensile strength of the conductor, D is the ratio of the circumferential dimension of the crimping portion in a state in which the crimping portion is crimped to the conductor to the overall circumferential length of the conductor, and E (N) is the connection strength between the crimping portion and the conductor.

6. A method for manufacturing an electric wire with a terminal, comprising the steps of: The terminal has at least a crimping portion capable of crimping a conductor wire, the crimping portion being formed in a substantially cylindrical shape, a conductor exposed from a tip of a coating portion of a coated conductor wire is inserted into the substantially cylindrical crimping portion and crimped by the crimping portion; A method for manufacturing an electric wire with a terminal, characterized in that the condition of 4≦(A×B×C×D) / E≦20 is satisfied, where A (mm) is the longitudinal dimension of the crimping portion, B (mm) is the total circumferential length of the conductor exposed on the outer periphery when the covering portion is removed, C (MPa) is the tensile strength of the conductor, D is the ratio of the circumferential dimension of the crimping portion in a state in which the crimping portion is crimped to the conductor to the overall circumferential length of the conductor, and E (N) is the connection strength between the crimping portion and the conductor.

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