Flat conductor and method for manufacturing flat conductor

Abstract

This flat conductor (1) is provided with a conductive plate material (2) having an elongated shape with a width larger than the thickness of a cross section orthogonal to the longitudinal direction. The plate material (2) is provided with: an end portion (3) in which at least one of both ends in the longitudinal direction of the plate material (2) is folded back at least once in the thickness direction so as to be in surface contact with a portion that is not folded back and which is electrically connected to another conductive member; and a central portion (5) which is a portion adjacent to the end portion (3) in the longitudinal direction. The thickness of the end portion (3) is greater than the thickness of the central portion (5), and the conductor resistance per unit length of the end portion (3) is lower than the conductor resistance per unit length of the central portion (5).

Description

Flat conductor and method for manufacturing the same

[0001] The present invention relates to a flat conductor and a method for manufacturing the flat conductor.

[0002] With the recent increase in electric vehicles, there has been an increasing demand for flat conductors, such as bus bars used in electric vehicle battery packs and under the floors of electric vehicles, as wiring components for large currents. However, flat conductors generate heat due to temperature rise caused by resistance when current is passed through them, so it is preferable to provide a structure that suppresses temperature rise. One example of a structure that suppresses temperature rise is a structure that uses a conductor with a different cross-sectional area in the longitudinal direction (see, for example, Patent Document 1). Another structure suppresses heat generation at the connection by connecting dissimilar metals with different conductivities in the longitudinal direction and using the metal with the higher conductivity as the connection point with another conductive material (see, for example, Patent Document 2).

[0003] Japanese Patent Publication No. 2014-229384 Japanese Patent Publication No. 2020-113524

[0004] The structure of Patent Document 1 involves forming a T-shaped conductive plate by press-punching a plate material, which has a long plate-like main body portion and a plate-like bulging portion that bulges from the main body portion in a width direction perpendicular to the longitudinal direction of the main body portion, and then folding the bulging portion back toward the main body portion to increase the cross-sectional area of ​​the central portion. Therefore, the plate material remaining after punching has a T-shaped hole and becomes waste material that cannot be used for further punching. Therefore, when manufacturing parts with the structure of Patent Document 1, the waste material is generated, which tends to result in a low yield rate and low productivity.

[0005] Furthermore, the method of joining dissimilar metals as described in Patent Document 2 requires a step of forming the metals to be joined into the desired dimensions and shape by cutting the metal sheets or the like, and a step of joining the metals formed into the desired dimensions and shapes together, which increases the number of steps and results in low productivity.

[0006] The present invention has been made to solve such problems, and its purpose is to provide a flat conductor and a method for manufacturing a flat conductor that can improve productivity while suppressing temperature rise when current is applied.

[0007] The flat conductor of the present invention is a flat conductor comprising a long, conductive plate material whose width is greater than the thickness of a cross section perpendicular to the longitudinal direction, and at least one of the longitudinal ends of the plate material is folded back at least once in the thickness direction to make surface contact with the unfolded portion and to be electrically connected to other conductive members, and a central portion which is adjacent to the end portion in the longitudinal direction, and the thickness of the end portion is greater than the thickness of the central portion, and the conductor resistance per unit length of the end portion is lower than the conductor resistance per unit length of the central portion.

[0008] The method for manufacturing a flat conductor of the present invention includes a preparation step of preparing a long, conductive plate material that is wider than the thickness of a cross section perpendicular to the longitudinal direction, and a folding step of folding at least one of the two ends of the plate material at least once in the thickness direction and bringing it into surface contact with the unfolded part to form an end portion that is electrically connected to another conductive member, wherein in the folding step, the end portion is formed so that the thickness of the end portion is thicker than the thickness of the central portion, which is the portion adjacent to the end portion in the longitudinal direction, and so that the conductor resistance per unit length of the end portion is lower than the conductor resistance per unit length of the central portion.

[0009] According to the present invention, it is possible to provide a flat conductor and a method for manufacturing the flat conductor that can improve productivity while suppressing a temperature rise when current is applied.

[0010] 10 is a perspective view showing a flat conductor according to the present embodiment. FIG. 1 is a side view of FIG. 1. (a) is a cross-sectional view taken along line A-A in FIG. 2, and (b) is a cross-sectional view taken along line B-B in FIG. 2. FIG. 11 is a cross-sectional view showing first and second modified examples of the flat conductor according to the present embodiment, and is a cross-sectional view of a portion corresponding to the cross-section A-A in FIG. 2. FIG. 12 is a perspective view showing a third modified example of the flat conductor according to the present embodiment. FIG. 13 is a perspective view showing a fourth modified example of the flat conductor according to the present embodiment. FIG. 14 is a perspective view showing a fifth modified example of the flat conductor according to the present embodiment. FIG. 15 is a side view showing a sixth modified example of the flat conductor according to the present embodiment. FIG. 16 is a side view showing a procedure for a method for manufacturing the flat conductor according to the present embodiment. FIG. 17 is a side view showing a procedure for a method for manufacturing the flat conductor according to the present embodiment. FIG. 18 is a graph showing the results of a simulation of the relationship between the current flow time and the temperature at the center when current is passed through flat conductors of the example and the comparative example.

[0011] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments shown below, some components are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are applied as appropriate to the details of the omitted technologies within the scope of the content described below.

[0012] 1 to 3 are diagrams showing a flat conductor according to this embodiment. The flat conductor 1 is a busbar that is arranged, for example, in a battery pack or under the floor of an electric vehicle as a wiring member for a battery that is the power source of the vehicle, and is configured with a conductive plate material 2. As shown in FIGS. 1 and 2, the plate material 2 is elongated. As shown in FIG. 3(a), the width W of the plate material 2 is greater than the thickness t of the A-A cross section perpendicular to the longitudinal direction. There are no particular restrictions on the material of the plate material 2 as long as it is conductive, but copper, aluminum, or magnesium is preferred because it has excellent conductivity, good processability, and is not extremely expensive.

[0013] As shown in Figures 1 and 2, the plate material 2 has end portions 3 and a central portion 5. The end portions 3 are portions that are electrically connected to other conductive members such as bolts and terminals. Specifically, the end portions 3 are portions where at least one of both ends in the longitudinal direction of the plate material 2, in this case both ends, are folded back at least once in the thickness direction and are in surface contact with the non-folded portion (see non-folded portion 9 in Figure 1). The end portions 3 shown in Figure 2 have one end portion 3a where one end in the longitudinal direction is folded back, and another end portion 3b where the other end in the longitudinal direction is folded back.

[0014] More specifically, the end portion 3 has a folded portion 7 and a non-folded portion 9. The folded portion 7 is a plate-shaped portion formed by folding back an end of the plate material 2. The non-folded portion 9 is a portion that is not folded back and is a portion with which the folded portion 7 makes surface contact. The end portion 3 shown in FIG. 2 has both ends folded back once, forming a U-shape with the folded portion 7 and the non-folded portion 9. Furthermore, the end portion 3 has a contact surface 11 where opposing surfaces of the U make surface contact. The central portion 5 is a portion adjacent to the end portion 3 in the longitudinal direction, in this case the portion between a pair of end portions 3, and is a portion that electrically connects both ends of the flat conductor 1.

[0015] As shown in Figures 3(a) and 3(b), the thickness T of the end portion 3 is greater than the thickness t of the central portion 5. Furthermore, the conductor resistance per unit longitudinal length of the end portion 3 is lower than the conductor resistance per unit longitudinal length of the central portion 5. Furthermore, since the thickness T of the end portion 3 of the flat conductor 1 is greater than the thickness t of the central portion 5, the thermal capacity of the end portion 3 is greater than that of the central portion 5. Therefore, by connecting another conductive member to the end portion 3 of the flat conductor 1 and passing current through it, even if the flat conductor 1 is heated by circuit resistance such as the electrical resistance of the plate material 2 or the contact resistance between the end portion 3 and another conductive member, the temperature of the end portion 3 is less likely to rise, thereby suppressing heat generation in the end portion 3. Furthermore, the folded portion 7 of the end portion 3 also functions as a heat sink, thereby improving the heat dissipation of the end portion 3. Furthermore, the folded portion 7 and the non-folded portion 9 are integrated into a U-shape via a fold (see connection portion 15 in Figure 9 ). Therefore, even if the plate material 2 vibrates due to the usage environment, the folded portion 7 and the non-folded portion 9 mutually prevent their positions from shifting, which prevents the folded portion 7 and the non-folded portion 9 from moving apart due to vibration, thereby preventing an increase in the conductor resistance of the end portion 3. In this way, the end portion 3 can prevent a temperature increase when current is passed through the flat conductor 1.

[0016] Furthermore, since the end portion 3 is formed by folding back at least one of the longitudinal ends of the plate material 2, the flat conductor 1 can be manufactured simply by manufacturing the plate material 2 in a long shape, cutting the plate material 2 to a length that is the length required for the flat conductor 1 plus the length of the folded-back portion 7, and folding back the end portion. Therefore, the flat conductor 1 does not need to be manufactured using a manufacturing method that generates a large amount of waste material, such as press punching, and the yield rate during manufacturing can be improved.

[0017] Furthermore, because the end portions 3 are connected to other conductive members, they are more likely to generate heat than the central portion 5. Therefore, by making the thickness T of the end portions 3 thicker than the thickness t of the central portion 5 to suppress heat generation in the end portions 3, the temperature rise of the flat conductor 1 during current flow can be suppressed compared to when the thickness t of the central portion 5 is thicker than the thickness T of the end portions 3. Furthermore, in a long member such as the plate material 2, when folding back the central portion 5, it is necessary to form a folding portion separately from the long portion, for example, by forming the central portion into a T-shape. However, such a portion is not necessary for the end portions 3, so the end portions 3 are easier to fold back than the central portion 5. Therefore, a structure in which the fold portion 7 is provided at the end portions 3 is advantageous in terms of productivity when manufacturing the flat conductor 1 by folding back the end portions 3 compared to a structure in which the central portion 5 is folded back.

[0018] 1 is preferably larger than the conductor cross-sectional area S2, which is the cross-sectional area perpendicular to the longitudinal direction of the central portion 5 shown in Fig. 3(a). Since the area S1 of the contact surface 11 is larger than the conductor cross-sectional area S2, the contact resistance of the contact surface 11 is smaller than the conductor resistance per unit area of ​​the central portion 5. Therefore, there is no need to worry about an increase in the amount of heat generated at the contact surface 11 when a current flows through the flat conductor 1.

[0019] The longer the length L1 of the end portion 3 shown in Figure 2, the more effectively it suppresses the temperature rise of the flat conductor 1 during current application. The shorter the length, the shorter the length of the folded plate 2, resulting in lower costs. Therefore, the length L1 can be selected appropriately based on the degree of suppression of temperature rise during current application and cost. The overall length L2 of the flat conductor 1 shown in Figure 2 can be set based on the distance between the other conductive member connected to one end portion 3a and the other conductive member connected to the other end portion 3b. The larger the width W and thickness t of the central portion 5 of the plate 2 shown in Figure 3(a) and the thickness T of the end portion 3 shown in Figure 3(b), the more effectively it suppresses the temperature rise of the flat conductor 1 during current application and the stronger the plate 2 becomes. The smaller the width W, thickness t, and T, the smaller the dimensions of the plate 2, resulting in lower costs. Therefore, the width W, thickness t, and T can be selected appropriately based on the degree of suppression of temperature rise during current application and cost.

[0020] FIG. 4( a) is a cross-sectional view showing a first modified example of the flat conductor 1 according to this embodiment. As shown in FIG. 4( a), the flat conductor 1 may have an insulator 21 coated on the surface of the plate material 2. Coating the surface of the plate material 2 with the insulator 21 prevents short circuits caused by unintended contact between the flat conductor 1 and other components around the area where the flat conductor 1 is installed, as well as damage to the surface of the plate material 2. Since the contact surface 11 between the folded portion 7 and the non-folded portion 9 must be electrically conductive, if the contact surface 11 is coated with the insulator 21, the insulator 21 must be removed before folding. If the insulator 21 is provided in the central portion 5 as shown in FIG. 4( a), if the folded portion 7 is to be formed in the central portion 5, the insulator 21 in the central portion 5 must be removed and folded, and then the central portion 5 must be re-coated with the insulator 21. On the other hand, the end portion 3 is connected to other conductive components, and if the insulator 21 is present, it must be removed. Therefore, the process of re-coating the insulator 21 after forming the folded portion 7 is unnecessary. Therefore, the structure in which the folded portion 7 is formed at the end portion 3 requires fewer steps to provide the folded portion 7 than the structure in which the folded portion 7 is provided at the center portion 5. Therefore, when the insulating material 21 is covered, the effect of forming the folded portion 7 at the end portion 3 is particularly high.

[0021] 4(b) and 5 are a cross-sectional view showing a second modified example of the flat conductor 1 according to this embodiment and a perspective view showing a third modified example. As shown in FIG. 4(b), the flat conductor 1 may be protected by covering the plate material 2 with an insulating protector 23. Furthermore, as shown in FIG. 5, the flat conductor 1 may be protected by covering the central portion 5 of the plate material 2 with insulating tape 25. Protecting the plate material 2 prevents damage to the surface of the plate material 2 due to unintended contact with other components, and also prevents short circuits due to unintended contact with other components.

[0022] Fig. 6 is a perspective view showing a fourth modified example of the flat conductor 1 according to this embodiment. As shown in Fig. 6, the flat conductor 1 may have a crimp terminal 27 provided at the end portion 3. The crimp terminal 27 shown in Fig. 6 includes a crimp portion 27a and a terminal portion 27b. The crimp portion 27a is a rectangular cylindrical member crimped to the end portion 3, and is provided in contact with the left and right side surfaces, top surface, and bottom surface of the end portion 3 so as to surround the end portion 3, and is electrically connected to the end portion 3 by crimping. The terminal portion 27b is a plate-shaped member connected to another conductive member, and protrudes from the lower end of the crimp portion 27a toward the outside in the longitudinal direction of the plate material 2 (the opposite side from the central portion 5).

[0023] As a result of the flat conductor 1 having the crimp terminal 27, the folded portion 7 and the non-folded portion 9 of the end portion 3 are fastened to the crimp portion 27a and pressed against each other. Therefore, even if the plate material 2 vibrates due to the usage environment, the folded portion 7 and the non-folded portion 9 are more effectively prevented from shifting from one another.

[0024] Fig. 7 is a perspective view showing a fifth modification of the flat conductor 1 according to this embodiment. As shown in Fig. 7, the flat conductor 1 may have a hole 29 at the end 3 through which a bolt, which is another conductive member, is inserted. By providing the hole 29, a bolt (not shown) can be passed through a through-hole (not shown) in the other conductive member and the hole 29 in the flat conductor 1, and then a nut (not shown) or the like can be fastened to the bolt to tighten the flat conductor 1. This structure is advantageous in that it does not require a separate terminal for bolt fastening.

[0025] FIG. 8 is a side view showing a sixth modification of the flat conductor 1 according to this embodiment. As shown in FIG. 8 , the end 3 of the flat conductor 1 may be folded back two or more times in the thickness direction at the longitudinal end of the plate material 2 (FIG. 8 illustrates a case where the end 3 is folded back two or more times). In this case, the end 3 may have a spiral shape as shown in FIG. 8( a). Alternatively, the end 3 may have a corrugated (bellows) shape as shown in FIG. 8( b). Thus, the end may be folded back two or more times. The more the number of folds, the thicker the thickness T of the end 3 shown in FIG. 3( b) can be, which increases the thermal capacity and improves the effect of suppressing temperature rise during current application. On the other hand, the fewer the number of folds, the shorter the longitudinal length of the plate material 2, thereby reducing the cost of the flat conductor 1. Therefore, the number of folds can be appropriately selected based on the balance between the effect of suppressing temperature rise during current application and the cost of the flat conductor 1.

[0026] As described above, the flat conductor 1 of this embodiment includes a plate member 2 having end portions 3 and a central portion 5. The end portions 3 are folded back at least once along the thickness direction of the plate member 2, making surface contact with the unfolded portions. The thickness T of the end portions 3 is greater than the thickness t of the central portion 5. Furthermore, the conductor resistance per unit length of the end portions 3 is lower than that of the central portion 5. Therefore, the heat capacity of the end portions 3 is greater than that of the central portion 5. Therefore, even when current is applied to the flat conductor 1, the temperature of the end portions 3 is less likely to rise, suppressing heat generation in the end portions 3 and improving heat dissipation from the end portions 3. Furthermore, because the folded portion 7 and the non-folded portion 9 of the end portions 3 are integrated into a U-shape via a fold, the folded portion 7 and the non-folded portion 9 mutually prevent misalignment even when the plate member 2 vibrates. This also prevents the folded portion 7 and the non-folded portion 9 from separating due to vibration, thereby preventing an increase in conductor resistance.

[0027] Furthermore, the end portions 3 are formed by folding both longitudinal ends of the plate material 2 back in the thickness direction, and do not need to be formed using a manufacturing method that generates a large amount of waste material, such as press punching, so the flat conductor 1 can have a high yield rate during manufacturing.

[0028] 9 to 11 are side views showing an example of a manufacturing method of the flat conductor 1. When manufacturing the flat conductor 1, first, as shown in Fig. 9, a long conductive plate material 2 (see Fig. 3(a)) is prepared, the width W of which is greater than the thickness t of the cross section perpendicular to the longitudinal direction (preparation step). In this embodiment, the central portion 5 is not subjected to processing such as rolling during the manufacturing of the flat conductor 1, so the thickness t of the plate material 2 is the same as the thickness t of the central portion 5. The longitudinal length L of the plate material 2 total The length L1 of the folded portion 7 (end 3) can be obtained by cutting a long member of the desired thickness, for example, to obtain the total length L2 of the flat conductor 1. In FIG. 9, there are two folded portions 7, so the length L1 of FIG. total To be precise, the length is the total length L2 plus approximately twice the length L1.

[0029] Next, as shown by arrow C in Fig. 9 , at least one of the ends of the plate material 2, in this case both, is folded back at least once in the thickness direction, along the connection 15 between the folded back portion 7 and the non-folded portion 9. Furthermore, as shown by arrow D in Fig. 10 , the folded back portion 7 is pressed against the non-folded portion 9 to bring them into surface contact, thereby forming a pair of end portions 3 that are electrically connected to other conductive members (folding process). In the folding process, the end portions 3 are formed so that the thickness T of the end portions 3 is greater than the thickness t of the central portion 5, and so that the conductor resistance per unit length of the end portions 3 is lower than the conductor resistance per unit length of the central portion 5.

[0030] 9 and 10 show the case where both ends of the plate material 2 are folded back once, but when folding back twice, the end portions 3 are formed by the procedure shown in Fig. 11. Specifically, as shown in Figs. 11(a) to 11(c), both ends of the plate material 2 are repeatedly folded back on one of the upper and lower surfaces, in this case the upper surface, to form the spiral end portions 3. Alternatively, as shown in Figs. 11(d) to 11(f), both ends of the plate material 2 are folded back alternately on the lower surface and the upper surface to form the corrugated (accordion-like) end portions 3.

[0031] As described above, in the manufacturing method of the flat conductor 1 of this embodiment, by folding both ends of the plate material 2 in the thickness direction, the thickness T of the end portion 3 is made thicker than the thickness t of the central portion 5, and the conductor resistance per unit length of the end portion 3 is made lower than the conductor resistance per unit length of the central portion 5. Furthermore, by making the thickness T of the end portion 3 thicker than the thickness t of the central portion 5, the heat capacity of the end portion 3 is made larger than the heat capacity of the central portion 5. Therefore, even when current is applied to the flat conductor 1, heat generation in the end portion 3 can be suppressed, and a flat conductor 1 with improved heat dissipation performance can be manufactured. Furthermore, in the manufacturing method of the flat conductor 1 of this embodiment, the end portion 3 is formed by folding the end of the plate material 2 in the thickness direction, so the folded portion 7 and the non-folded portion 9 are integrated into a U-shape via the fold (connection portion 15). Therefore, even when the plate material 2 vibrates, the folded portion 7 and the non-folded portion 9 mutually prevent misalignment. This also prevents the folded portion 7 and the non-folded portion 9 from separating due to vibration, thereby suppressing an increase in the conductor resistance of the end portion 3.

[0032] Furthermore, in the manufacturing method of the flat conductor 1 of this embodiment, the end portions 3 are formed by folding back both longitudinal ends of the plate material 2 in the thickness direction, so there is no need to use a manufacturing method that generates a large amount of waste material, such as press punching. Therefore, the manufacturing method of the flat conductor 1 of this embodiment can manufacture the flat conductor 1 with a good yield.

[0033] The present invention will be described in detail below based on examples, but is not limited to these examples. A computer simulation was used to determine the relationship between the temperature of the central portion 5 and time when a current is passed through a flat conductor 1 in which both longitudinal ends of a plate material 2 are folded back in the thickness direction to form end portions 3. Furthermore, the relationship between the temperature of the central portion 5 and time when both ends are not folded back was also determined by computer simulation, and the degree of temperature rise when a current is passed through was compared. The specific procedure is as follows.

[0034] Example 1 A simulation was performed using the thermal fluid analysis tool "Ansys Icepak" manufactured by ANSYS, Inc., according to the following procedure. First, a model of a flat conductor 1 was prepared in which both ends of an aluminum plate 2 having a thickness of 5 mm, a width of 24 mm, and a length of 500 mm were folded back once to a length of 30 mm each, so that the thickness T of the end 3 was 10 mm. Next, a direct current of 400 A was passed through the prepared model for 1200 seconds, and the temperatures at the center positions in the longitudinal and width directions of the central portion 5 were measured with a data logger using a thermocouple model attached at the center position.

[0035] (Example 2) A model was prepared under the same conditions as in Example 1, except that the number of folds was two, the fold shape was wavy (accordion-like), and the thickness T of the end portion 3 was 15 mm.The temperatures at the center positions in the longitudinal and width directions of the central portion 5 were calculated under the same conditions as in Example 1.

[0036] Comparative Example A model was prepared under the same conditions as in Example 1 except that both ends were not folded back, and the temperatures at the center positions in the longitudinal and width directions of the central portion 5 were calculated under the same conditions as in Example 1.

[0037] The relationship between the current application time and the temperature of the central portion 5 of the models of Example 1, Example 2, and Comparative Example is shown in Figure 12. As is clear from Figure 12, in Examples 1 and 2 in which both ends were folded back, the temperature of the central portion 5 was lower when the current application time was the same than in the Comparative Example in which both ends were not folded back. This result shows that folding back both ends of the plate material 2 can suppress the temperature rise in the central portion 5. Furthermore, when Example 1 and Example 2 are compared, the temperature of the central portion 5 is lower in Example 2 when the current application time is the same. Therefore, it was found that the temperature rise can be further suppressed by increasing the number of folds and increasing the thickness T of the end portion 3.

[0038] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the present invention, and other techniques may be appropriately combined to the extent possible. Furthermore, publicly known or well-known techniques may be combined to the extent possible.

[0039] For example, in the above embodiment, the thickness T is made thicker than the thickness t of the central portion 5 by folding back both ends 3 of the plate material 2, but if there is not enough space to make the thickness T of one end 3 thicker than the thickness t of the central portion 5, only one end 3 may be folded back.

[0040] In the above embodiment, the one end 3a and the other end 3b are illustrated as having the same thickness T and the same longitudinal length L1. However, if the heat generation amounts of the one end 3a and the other end 3b differ due to differences in other conductive members connected thereto, the thickness T and the longitudinal length L1 of the one end 3a and the other end 3b may be different from each other.

[0041] Here, the features of the flat conductor and the method for manufacturing the flat conductor according to the above-described embodiments of the present invention are briefly summarized and listed below in [1] to [6]. [1] A flat conductor (1) comprising a long, conductive plate material (2) having a width greater than the thickness of a cross section perpendicular to the longitudinal direction, wherein at least one of the longitudinal ends of the plate material (2) is folded back at least once in the thickness direction, and the plate material (2) comprises: an end portion (3) that is in surface contact with the unfolded portion and is electrically connected to another conductive member; and a central portion (5) that is adjacent to the end portion (3) in the longitudinal direction, wherein the thickness of the end portion (3) is greater than the thickness of the central portion (5), and the conductor resistance per unit length of the end portion (3) is lower than the conductor cross-sectional area per unit length of the central portion (5). [2] The flat conductor according to the above [1], wherein the area of ​​the surface contact surface of the end portion (3) is greater than the conductor cross-sectional area of ​​the central portion (5) that is the cross-sectional area perpendicular to the longitudinal direction. [3] The flat conductor according to the above [1] or [2], wherein the surface of the plate material (2) is covered with an insulator (21), or with a protector (23) or tape (25). [4] The flat conductor according to the above [1] or [2], wherein the plate material (2) is made of copper, aluminum, or magnesium. [5] The flat conductor according to the above [1] or [2], wherein the flat conductor has a crimp terminal (27) provided at the end (3) and connected to the other conductive member, or a hole (29) provided at the end (3) and through which a bolt is inserted when the flat conductor is bolt-fastened to the other conductive member.[6] A method for manufacturing a flat conductor, comprising: a preparation step of preparing a long conductive plate material (2) having a width greater than the thickness of a cross section perpendicular to the longitudinal direction; and a folding step of folding back at least one of both ends of the plate material (2) at least once in the thickness direction and bringing it into surface contact with the unfolded part, thereby forming an end portion (3) that is electrically connected to another conductive member, wherein in the folding back step, the end portion (3) is formed so that the thickness of the end portion (3) is greater than the thickness of a central portion (5) that is a portion adjacent to the end portion (3) in the longitudinal direction, and so that the conductor resistance per unit length of the end portion (3) is lower than the conductor resistance per unit length of the central portion (5).

[0042] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0043] This application is based on a Japanese patent application (Patent Application No. 2024-049222) filed on March 26, 2024, the contents of which are incorporated herein by reference.

[0044] According to the present invention, it is possible to improve productivity while suppressing a temperature rise during current application, and it is useful for a flat conductor and a method for manufacturing a flat conductor.

[0045] 1: Flat conductor 2: Plate material 3: End portion 5: Center portion 7: Folded portion 11: Contact surface 21: Insulator 23: Protector 25: Tape 27: Crimp terminal 29: Hole portion S1: Area S2: Conductor cross-sectional area T: Thickness W: Width t: Thickness

Claims

1. A flat conductor comprising a long, conductive plate material whose width is greater than the thickness of a cross section perpendicular to the longitudinal direction, wherein at least one of the longitudinal ends of the plate material is folded back at least once in the thickness direction to form end portions that are in surface contact with the unfolded portion and are electrically connected to other conductive members, and a central portion that is adjacent to the end portions in the longitudinal direction, wherein the thickness of the end portions is greater than the thickness of the central portion, and the conductor resistance per unit length of the end portions is lower than the conductor resistance per unit length of the central portion.

2. The flat conductor according to claim 1, wherein the area of ​​the contact surface of the end portion is larger than the conductor cross-sectional area of ​​the central portion, which is the cross-sectional area perpendicular to the longitudinal direction.

3. The flat conductor according to claim 1 or 2, wherein the surface of the plate material is coated with an insulator or covered with a protector or tape.

4. The flat conductor according to claim 1 or 2, wherein the plate material is at least one of copper, aluminum, and magnesium.

5. A flat conductor as claimed in claim 1 or 2, having a crimp terminal provided at the end portion and connected to the other conductive member, or a hole provided at the end portion and through which a bolt is inserted when the flat conductor is bolted to the other conductive member.

6. A method for manufacturing a flat conductor, comprising: a preparation step of preparing a long, conductive plate material that is wider than the thickness of a cross section perpendicular to the longitudinal direction; and a folding step of folding at least one of the two ends of the plate material at least once in the thickness direction and bringing it into surface contact with the unfolded part to form an end portion that is electrically connected to another conductive member, wherein in the folding step, the end portion is formed so that it is thicker than the thickness of a central portion that is adjacent to the end portion in the longitudinal direction, and so that the conductor resistance per unit length of the end portion is lower than the conductor resistance per unit length of the central portion.

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