Copper bus bar

Abstract

The present invention relates to a bare bus bar structure for application to an electric vehicle battery pack, and a production method thereof, and, more specifically, relates to a method with which continuous production is possible and to structural design technology that ensures electrical stability and improves automatic bending workability, by forming each corner of a bus bar in an optimal round shape.

Description

copper busbar

[0001] The present invention relates to a copper bare bus bar, and relates to an invention for ensuring electrical stability, preventing fire, and enabling application to a narrow space of an electric vehicle battery pack through the structural design of a bare bus bar.

[0002]

[0003] Busbars can be broadly categorized into flexible busbars and rigid press busbars. Flexible busbars are manufactured by laminating and welding thin, flat plates, then pressing them to form the busbar conductors. After inserting an insulating tube, manual bending (mounting the conductors on a jig and then bending them) is performed. Rigid busbars are manufactured by pressing thick plates to form the conductors, then coating them with an epoxy insulation layer or inserting an injection-molded material into the conductors.

[0004] Conventional flexible busbars require a complex manufacturing process involving laminating thin, flat sheets. Their flexible structure, difficult to secure, hinders automation, increasing manufacturing costs. Rigid busbars, manufactured by pressing sheets, generate significant scrap losses. Furthermore, they cannot be manufactured in long sections, and bobbin winding is impossible.

[0005] Each corner of the press-processed busbar is square, and when current is applied to the square area (corner), a current bottleneck phenomenon occurs, which increases the possibility of fire due to heat generation in the busbar. In addition, when mica taping is used to prevent flames from the busbar, the tape is likely to be damaged at the sharp corners. In addition, when the insulation coating is extruded, the insulation thickness at the sharp corners is thin, which increases the possibility of fire due to leakage due to insulation breakdown. In addition, when the corners are sharp, shrinkage / expansion at the bending area is large, making it difficult to remove the product from the jig after bending and causing poor appearance.

[0006]

[0007] The present invention is intended to solve the above problems and to provide a busbar structure that is rigidly developed to enable an automated busbar process, and that secures electrical stability by optimally designing each corner of a bare busbar into a long oval track round type structure to prevent heat generation at the corners when current is applied, and reduces deviations in expansion and contraction during automatic bending, thereby improving workability.

[0008] In addition, the present invention aims to provide a manufacturing method that is simple in process and allows continuous production, thereby reducing costs.

[0009]

[0010] According to one embodiment of the present invention, a copper bare busbar has a rectangular shape in which a width (W) is longer than a thickness (T) in a cross-sectional shape perpendicular to the longitudinal direction and a curvature is given to four corners to form a curved shape, and the radius of curvature (R) is 0.4 to 0.6 of the thickness (T) (T×0.4 ≤ R ≤ T×0.6).

[0011] The above radius of curvature (R) is greater than 0.4 and less than or equal to 0.6 of the thickness (T). (T×0.4 <R ≤ T×0.6)

[0012] It additionally includes an insulating layer formed with a uniform thickness on the outside of the copper bare busbar.

[0013] A curve is formed by forming a sector-shaped arc of radius R from the center of a point located inside the rectangle at a constant distance from each corner of the rectangle, and the distance between the centers of the sector-shaped arcs parallel to the long sides of the rectangle in the width direction is the width-side (A), and the distance between the centers of the sector-shaped arcs parallel to the short sides of the rectangle in the thickness direction is the thickness-side (B).

[0014] When the above radius of curvature (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5), and when A = W - 2R and B = T - 2R, a 90-degree arc of a fan shape with a radius R is formed from the center of a point located inside the rectangular shape moved by the length of the radius of curvature (R) in the width direction and the thickness direction from each corner of the rectangular shape, thereby forming a curved shape.

[0015] When the above curvature radius (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5), and when at least one of A > W - 2R and B > T - 2R, a curved shape is formed by forming an acute angle of a fan-shaped arc of radius R at the center of a point located inside the rectangular shape that is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction.

[0016] When forming the above acute angle, starting from the point of the width opposite side (A) of the rectangle, an arc of the acute angle fan is formed up to the width length, and the thickness opposite side (B) forms a straight line.

[0017] When the above radius of curvature (R) is greater than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), A = W-2x[R 2-(R-0.5T) 2 ] 0.5 And when B = 0, a curve is formed by forming an acute angle of a fan-shaped arc of radius R at the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction.

[0018] When the above radius of curvature (R) is greater than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), A > W-2x[R 2 -(R-0.5T) 2 ] 0.5 And if B > 0, a curve is formed by forming an acute angle of a fan-shaped arc of radius R at the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction.

[0019] When forming the above acute angle, starting from the point of the width opposite side (A) of the rectangle, an arc of the acute angle fan is formed up to the width length, and the thickness opposite side (B) forms a straight line.

[0020] The above width (W) is 2 to 7 times the above thickness (T).

[0021] The above width (W) is 5 to 50 mm, and the thickness (T) is 2 to 20 mm.

[0022] The above copper bare busbar is manufactured by the CONFORM extrusion process.

[0023] The above copper bare busbar is used as an electric vehicle battery pack or power line for a vehicle. Additionally, the above copper bare busbar is used in a battery pack for an energy storage system.

[0024]

[0025] The bare busbar structure according to the present invention prevents heat generation at each corner when current is applied, thereby preventing fire. In addition, each corner of the busbar cross-section is designed with an optimal track round type structure, thereby preventing tape damage during mica taping, and ensuring a uniform insulation thickness during insulation coating extrusion, thereby preventing fire caused by leakage due to insulation breakdown.

[0026] Furthermore, the bare busbar structure according to the present invention is rigidly developed to enable automated bending, and its rounded corners facilitate easy removal and installation of the bending jig, thereby improving workability. Furthermore, when installed in narrow spaces within an electric vehicle battery pack, the rounded corners of the bare busbar cross-section minimize interference with other components compared to square corners.

[0027] In addition, the manufacturing method according to the present invention can reduce manufacturing costs and minimize scrap generation because the process is simple and continuous production is possible.

[0028] Additionally, additional cost savings are possible due to the optimal ratio structure of bare busbar thickness and width that can increase the productivity of the manufacturing method.

[0029]

[0030] FIG. 1 illustrates a cross-sectional view perpendicular to the longitudinal direction of a bare bus bar according to one embodiment of the present invention.

[0031] FIG. 2 illustrates a cross-sectional shape of a bare busbar according to the prior art and a cross-sectional shape of a bare busbar according to an embodiment of the present invention, respectively.

[0032] FIG. 3 illustrates a design diagram for explaining a bare busbar structure according to one embodiment of the present invention.

[0033] Figure 4 shows the appearance of the bare busbar structure when R is T x 0.1.

[0034] Figure 5 shows the appearance of the bare busbar structure when R is T x 0.4.

[0035] Figure 6 shows the appearance of the bare busbar structure when R is T x 0.5.

[0036] Figure 7 shows the appearance of the bare busbar structure when R is T x 0.6.

[0037] Figure 8 shows the cross-sectional structure of a conventional square type extruded busbar and the track round type extruded busbar structure according to the present invention.

[0038] Figure 9 shows the change in thickness according to position when a bare busbar is insulated, extruded, and bent.

[0039] Figure 10 shows a schematic diagram of cross-sectional changes during bending.

[0040] Figure 11 shows a result drawing of the electrical characteristics of the copper bare busbar according to its structure.

[0041] Various embodiments are now described with reference to the drawings, wherein like reference numerals are used throughout the drawings to designate like elements. For purposes of explanation, various descriptions are provided herein to facilitate an understanding of the invention. However, it will be apparent that these embodiments may be practiced without these specific descriptions. In other instances, well-known structures and devices are presented in block diagram form to facilitate the description of the embodiments.

[0042]

[0043] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention is susceptible to various modifications and variations, and thus specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0044] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, steps, operations, components, parts, or combinations thereof.

[0045] In this specification, a bare bus bar means a bus bar in which the metal conductor is exposed as is without being coated with an insulating material.

[0046] In this specification, the Track Round Type refers to a shape in which a curve is formed in a round shape by giving curvature to each of the four corners of a rectangular shape, and the specific shape can be confirmed through the drawing.

[0047] The present invention proposes a busbar structure design that secures the electrical stability of a bare busbar to prevent fire and can be applied to narrow spaces in an electric vehicle battery pack. According to one aspect of the present invention, a busbar structure applicable to an electric vehicle battery pack is provided, in which the mica tape can be taped to the busbar without damage, the curvature radius of each corner of the busbar is designed to ensure a uniform insulation thickness during extrusion of the insulation coating, and excellent automatic bending workability. In addition, according to another aspect of the present invention, a CONFORM manufacturing method capable of simple and continuous production of busbars and a busbar for an electric vehicle battery pack designed with an optimal thickness and width ratio that can improve productivity are provided.

[0048] FIG. 1 illustrates a cross-sectional view perpendicular to the longitudinal direction of a bare bus bar according to one embodiment of the present invention.

[0049] As illustrated in FIG. 1, a copper bare busbar according to one embodiment of the present invention has a rectangular shape in which the width (W) is longer than the thickness (T) in a cross-sectional shape perpendicular to the longitudinal direction, and four corners are given curvatures to form a curved shape. For convenience, this shape is defined as a track round type in the present invention.

[0050] The bare busbar according to the present invention can be applied to an electric vehicle battery pack, and uses a copper material with a purity of 99.9% or higher and excellent elongation characteristics to secure electrical properties with a conductivity of 100% IACS or higher and automatic bending workability. It is preferable to use general electrolytic tough pitch copper and oxygen-free copper, and it is more preferable to use high-purity oxygen-free copper with an oxygen content of 10 ppm or less. Here, oxygen-free copper (OFC) is indicated by UNS (Unified Numbering System) alloy number C10100 or C10200 in ASTM B49, and electrolytic copper (ETP) is indicated by C11000 or C11040.

[0051] FIG. 2 illustrates a cross-sectional shape of a bare busbar according to the prior art and a cross-sectional shape of a bare busbar according to an embodiment of the present invention.

[0052] As shown in Fig. 2, the conventional square busbar on the left is manufactured by pressing a plate. In this case, in addition to the pressing method, it can also be manufactured through billet extrusion, rolling, and drawing processes. When a square-type bare busbar is applied for automatic bending, there is a problem in that the thickness expansion of the shrinkage portion is large during busbar bending, making it difficult to attach and detach the bare busbar from the bending jig. The middle picture of Fig. 2 illustrates a conventional edge round-type busbar. In the case of such an edge round busbar, a portion of the edge portion is curvatured, and the shrinkage portion expansion is less than that of the square type, so although detachment is possible, there is a problem in that appearance defects (nicks, scratches) occur. However, in the case of the track round-type busbar according to the present invention on the right, if the value of the curvature radius (R) of the edge, which is the corner, is applied to 40% or more of the thickness (T), it is easy to attach and detach from the bending jig without appearance defects.

[0053] Accordingly, a copper bare busbar according to one embodiment of the present invention has a curved shape in which four corners are given curvature in a rectangular shape in which a width (W) is longer than a thickness (T) in a cross-sectional shape perpendicular to the longitudinal direction, and the radius of curvature (R) is 0.4 to 0.6 of the thickness (T) (T×0.4 ≤ R ≤ T×0.6). More preferably, the radius of curvature (R) may be more than 0.4 and 0.6 or less of the thickness (T) (T×0.4 <R ≤ T×0.6).

[0054] FIG. 3 illustrates a design diagram for explaining a bare busbar structure according to one embodiment of the present invention.

[0055] As illustrated in Fig. 3, when looking at a cross-section perpendicular to the longitudinal direction of the bus bar, a curved shape is formed by forming a fan-shaped arc of radius R from the center of a point located inside the rectangular shape at a constant distance from each corner of the rectangular shape, and the distance between the centers of the fan-shaped arcs parallel to the long sides of the rectangle in the width direction is the width-corresponding side (A), and the distance between the centers of the fan-shaped arcs parallel to the short sides of the rectangle in the thickness direction is the thickness-corresponding side (B).

[0056] In this case, in selecting a point located inside a rectangular shape at a constant distance from each corner, the case can be divided into a case where the radius of curvature (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5) and a case where the radius of curvature (R) is more than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), and in each case, the selection of the point can be divided into a case where the point is located inside a rectangular shape moved by the length of the radius of curvature (R) in the width direction and the thickness direction from each corner of the rectangular shape, and a case where the point is located inside a rectangular shape moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction.

[0057] When the radius of curvature (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5), and when A = W - 2R and B = T - 2R, a fan-shaped arc of radius R is formed 90 degrees from the center of a point located inside the rectangular shape moved by the length of the radius of curvature (R) in the width direction and the thickness direction from each corner of the rectangular shape to form a curved shape. This shape corresponds to the shape of the upper drawing in FIGS. 4 to 6, respectively. FIG. 4 is when R is T x 0.1, and FIG. 5 is when R is T x 0.4. FIG. 6 is when R is T x 0.5, and the best mode in the present invention is when T x 0.5, in which case a track round type busbar having the smoothest curve can be obtained.

[0058] When the radius of curvature (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5), and when at least one of A > W - 2R and B > T - 2R, a sector-shaped arc of radius R is formed at an acute angle at the center of a point located inside the rectangular shape that is moved from each corner in the thickness direction by the radius of curvature (R) and in the width direction by a length shorter than the radius of curvature (R), thereby forming a curved shape. This shape corresponds to the shape of the lower drawing in FIGS. 4 to 6, respectively. As illustrated in FIGS. 4 to 6, the arc of the sector-shaped arc of radius R is formed by an acute angle less than 90 degrees, and in this case, starting from the point opposite the width side (A) of the rectangle, an acute-angle sector-shaped arc is formed up to the width length, and the opposite thickness side (B) forms a straight line.

[0059] Next, when the radius of curvature (R) is greater than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), A = W-2x[R 2 -(R-0.5T) 2 ] 0.5and when B = 0, a curve is formed by forming an acute angle of a fan-shaped arc of radius R at the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction. This shape corresponds to the shape of the upper drawing in Fig. 7, and Fig. 7 is when R is T x 0.6.

[0060] When the radius of curvature (R) is greater than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), A > W-2x[R 2 -(R-0.5T) 2 ] 0.5 And if B > 0, then a curved shape is formed by forming an acute-angled sector-shaped arc with a radius R from the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and moved by a length shorter than the radius of curvature (R) in the width direction. This shape corresponds to the shape of the lower drawing in Fig. 7. In this case, when forming an acute angle, an acute-angled sector-shaped arc is formed starting from the point opposite the width side (A) of the rectangle to the width length, and the opposite thickness side (B) forms a straight line.

[0061] Fig. 8 illustrates the cross-sectional structure of a conventional square type extruded busbar and the track round type extruded busbar structure according to the present invention, respectively. As seen on the left side of Fig. 8, in the case of the square type extruded busbar, the insulation thickness is thin at the edge portion, but in the case of the track round type extruded busbar structure of the present invention, as seen on the right side, the insulation thickness is uniform. In the case of the square type extruded busbar, due to the uneven insulation thickness, wrinkles may occur during bending, which becomes a vulnerable part, and there is a risk of fire due to leakage caused by insulation breakdown.

[0062] Figure 9 shows the change in thickness according to position when a bare busbar is insulated, extruded, and bent, and Figure 10 shows a schematic diagram of the change in cross-section when bending.

[0063] As shown in Fig. 9, when performing transverse bending, the thickness expands at position ① and contracts at position ②. The greater the expansion of the thickness at position ①, the more difficult it is for the bare busbar or insulated extruded busbar to be removed from the bending jig, resulting in poor workability and poor appearance (dents, scratches).

[0064] In Fig. 10, the upper drawing shows the contraction-expansion appearance when a square type busbar is bent, and it can be seen that the expansion is very large at position ① of Fig. 9, the middle drawing shows that the expansion is large at position ① of Fig. 9 even in the case of a conventional edge round type busbar, and the lower drawing shows the contraction-expansion appearance of a track round type busbar like the present invention, and it can be seen that the expansion is not large at position ① of Fig. 9.

[0065] Table 1 below compares the bending characteristics according to the structure of a copper bare busbar. When bending 180 degrees, the inner side of the bend expands and the outer side of the bend contracts. In this case, if the change in the thickness expansion rate and the thickness shrinkage rate are within the 10% range, the bending workability and surface quality are evaluated as excellent. As shown in Table 1 below, in the case of the square type, it can be confirmed that the thickness expansion rate is the highest because there is no empty space at the edge, and in the case of the edge round type, it can be confirmed that the thickness expansion rate exceeds 10% because the empty space in the round part is small. However, in the case of the track round type according to the present invention, it was confirmed that the thickness expansion rate is less than 10% because the round empty space is filled when the inner side expands due to bending in the entire cross-section, and the shrinkage rate in the thickness shrinkage part is also 10% or less.

[0066] Comparative Example 1, which is a conventional structure, has a high thickness expansion increase rate at the bending portion when evaluated with a conventionally used square bare busbar, making it difficult to attach and detach it when it gets caught in a bending jig, and the portion where the busbar gets caught in the bending jig experiences surface dents and scratches. Comparative Examples 2, 3, and 4 have an edge round type busbar structure in which each corner R value is 0.1 to 0.3 times the thickness T and has curvature at both ends of the thickness direction surface. Compared to the square type, the thickness expansion increase rate is lower and thus detachment from the bending jig is possible, but since there is no allowance, surface dents and scratches occur during the detachment process. Examples 5, 6, 7, and 8 have a track round type busbar structure in which each corner R value is 0.4 to 0.7 times the thickness T and has curvature at most of the thickness direction surface. Compared to the edge round type busbar structure, the thickness expansion increase rate is lower and thus detachment from the bending jig is good, and appearance defects such as surface dents and scratches do not occur during the detachment process. In summary, the track round type busbar structure has the smallest structural change with a thickness expansion rate and a shrinkage rate of less than 10%, and the thickness expansion rate must be less than 10% to prevent bending jig detachment and appearance quality defects. [Optimal R (mm) = T (mm) x 0.4 or more]

[0067]

[0068]

[0069]

[0070] Next, the electrical characteristics of the copper bare busbars were compared according to their structures.

[0071] As a comparative example with the track round type busbar according to the present invention, a square type busbar was manufactured, and specimens of the same length of 100 cm (uniformly manufactured at both ends) were manufactured, and the cross-sectional area size was 60 SQ. The evaluation equipment used an allowable current tester, with an applied current of 1000 A and an applied time of 10 min.

[0072] Figure 11 illustrates a schematic diagram of the electrical characteristics of a copper bare busbar according to its structure. As shown in Figure 11, in the case of a square-type busbar, the corners have a small cross-sectional area, so the current must pass through a narrow space, resulting in heat generation, which increases the possibility of power loss and fire. In contrast, in the case of the track round-type busbar according to the present invention, the corner curvature is gently relaxed, thereby preventing current bottlenecks and distributing the current flow more evenly, thereby reducing heat generation.

[0073] Next, we compared the withstand voltage evaluation and measured the electrical resistance after mica taping according to the structure of the copper bare busbar. The withstand voltage evaluation (2.6kV x 1min) was performed after taping the copper bare busbar with mica No. 1. The mica taping was performed using a mica taping machine, and the mica tape is composed of multiple layers, specifically, resin / glass cloth / uncalcined phlogopite mica paper / glass cloth. The electrical resistance of the copper bare busbar was measured using a 4-terminal electrical resistance meter on a 1m long busbar. Table 2 below summarizes the measurement results. As shown in Table 2, when mica taping was applied to a conventional square bare busbar, the tape tore due to excessive pressure from the sharp edges, resulting in a withstand voltage failure. On the other hand, as in Comparative Example 6, when the R value was 70% of T (i.e., R=0.7xT), a failure occurred due to exceeding the electrical resistance standard.

[0074]

[0075]

[0076] Table 3 below summarizes the results of bending workability and electrical characteristics for a conventional square type busbar, an edge round type busbar, and a track round type busbar of the present invention to secure bending workability and electrical characteristics. As shown in Table 3, it can be seen that the R value (mm) is preferably 0.4 to 0.6 of T (mm).

[0077]

[0078]

[0079] Meanwhile, the copper bare busbar according to the present invention is manufactured using a conform extrusion process. The track round type bare busbar can be manufactured using conventional manufacturing methods such as a rolling and drawing process or a billet extrusion process, but they have the following disadvantages. The rolling and drawing process is complicated and requires an additional heat treatment process. The billet extrusion process cannot be operated continuously and causes a lot of material loss. To overcome these disadvantages, the present invention continuously manufactures the busbar using a conform extrusion process, which is a severe plastic deformation (SPD) process. This conform extrusion process has the advantages of not requiring an additional heat treatment process, obtaining excellent mechanical properties by subjecting the busbar to severe plastic deformation and thereby refining the grains, and allowing for continuous processing, resulting in little material loss and a simple process.

[0080] In addition, conformal extrusion has fine grains, so it can secure excellent mechanical properties during automatic bending compared to busbars manufactured by conventional billet extrusion, and conformal extrusion can be connected and fed rod to rod, so continuous production is possible, but billet extrusion cannot be continuously produced because it cannot be connected to another billet once one billet is used up.

[0081] In the case of a copper bare busbar according to one embodiment of the present invention, the width (W) is preferably 2 to 7 times the thickness (T). Specifically, the width (W) may be 5 to 50 mm, and the thickness (T) may be 2 to 20 mm.

[0082] The width (W) of a track-type bare busbar for electric vehicle battery pack applications is preferably 5 to 50 mm. A width less than 5 mm will insufficiently dissipate heat, which is essential for high-voltage electric vehicle systems. This leads to increased electrical resistance due to increased temperature during current application, resulting in significant electrical losses. A width exceeding 50 mm will limit the space within the battery pack, making busbar installation difficult.

[0083] Additionally, the thickness (T) of the track round-type bare busbar for electric vehicle battery pack applications is preferably 2 to 20 mm. If the thickness is less than 2 mm, the busbar is more likely to be damaged when bolting after installation. Furthermore, the bolts may loosen due to weak tightening force. If the thickness exceeds 20 mm, the heat dissipation required for high-voltage electric vehicle systems is insufficient. Consequently, the increased temperature during current application leads to increased electrical resistance, resulting in significant electrical losses.

[0084] The optimal width-to-thickness ratio is as shown in Table 4 below. The optimal width (W) to thickness (T) value for improving conformal extrusion productivity and quality of track round type bare busbars is W (mm) = T (mm) x (2 to 7). If the width is less than twice the thickness, the surface area of ​​the busbar will be smaller for the same cross-sectional area, which will reduce the contact area between the conformal extrusion die and the material, increasing the possibility of surface defects due to material slip, which will hinder production speed. If the width exceeds seven times the thickness, deformation will occur due to warping of the flat opposite sides during the conformal extrusion process, which applies extreme plastic deformation, and surface scratches will occur due to difficulty in bobbin alignment winding. Therefore, increasing the width of track round type bare busbars from two to seven times the thickness can improve conformal extrusion productivity and prevent quality defects.

[0085]

[0086]

[0087] In summary, the R value for securing automatic bending workability and electrical stability is R (mm) = T (mm) x (0.4~0.6), and the width (W) value relative to thickness (T) for improving conform extrusion productivity and quality is W (mm) = T (mm) x (2~7), and the R value relative to W for securing automatic bending workability, electrical stability, and improving conform extrusion productivity and quality is R (mm) = W (mm) x (0.4~0.6) / (2~7).

[0088] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. As a copper bear busbar, In a cross-sectional shape perpendicular to the length direction, the width (W) is longer than the thickness (T), and the four corners are given curvature to form a curved shape. The radius of curvature (R) is 0.4 to 0.6 of the thickness (T) (T×0.4 ≤ R ≤ T×0.6), Copper bear busbar.

2. In paragraph 1, The above radius of curvature (R) is greater than 0.4 and less than or equal to 0.6 of the thickness (T) (T×0.4 <R ≤ T×0.6), Copper bear busbar.

3. In paragraph 1, In addition, an insulating layer formed with a uniform thickness on the outside of the copper bare busbar is included. Copper bear busbar.

4. In paragraph 1, A curve is formed by forming a fan-shaped arc of radius R from the center of a point located inside the rectangular shape at a constant distance from each corner of the rectangular shape. The distance between the centers of the arcs of the sector parallel to the long sides of the rectangle in the width direction is the width-parallel side (A), and the distance between the centers of the arcs of the sector parallel to the short sides of the rectangle in the thickness direction is the thickness-parallel side (B). Copper bear busbar.

5. In paragraph 4, When the above radius of curvature (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5), If A = W - 2R and B = T - 2R, A curve is formed by forming a fan-shaped arc of radius R 90 degrees from the center of a point located inside the rectangular shape, moved by the length of the radius of curvature (R) in the width direction and thickness direction from each corner of the rectangular shape. Copper bear busbar.

6. In paragraph 4, When the above radius of curvature (R) is 0.4 to 0.5 of the thickness (T) (T×0.4 ≤ R ≤ T×0.5), If at least one of A > W - 2R and B > T - 2R, A curved shape is formed by forming an acute angle of a fan-shaped arc of radius R from the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction. Copper bear busbar.

7. In paragraph 6, When forming the above acute angle, starting from the point of the width opposite side (A) of the rectangle, an arc of the acute angle is formed to the width length, and the thickness opposite side (B) forms a straight line. Copper bear busbar.

8. In paragraph 4, When the above radius of curvature (R) is greater than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), A = W-2x[R 2 -(R-0.5T) 2 ] 0.5 and if B = 0, A curved shape is formed by forming an acute angle of a fan-shaped arc of radius R from the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction. Copper bear busbar.

9. In paragraph 4, When the above radius of curvature (R) is greater than 0.5 and less than or equal to 0.6 of the thickness (T) (T×0.5 <R ≤ T×0.6), A > W-2x[R 2 -(R-0.5T) 2 ] 0.5 and if B > 0, then A curve is formed by forming an acute angle of a fan-shaped arc of radius R from the center of a point located inside the rectangular shape, which is moved by the radius of curvature (R) in the thickness direction from each corner of the rectangular shape and by a length shorter than the radius of curvature (R) in the width direction. Copper bear busbar.

10. In paragraph 9, When forming the above acute angle, starting from the point of the width opposite side (A) of the rectangle, an arc of the acute angle is formed to the width length, and the thickness opposite side (B) forms a straight line. Copper bear busbar.

11. In paragraph 1, The above width (W) is 2 to 7 times the above thickness (T), Copper bear busbar.

12. In paragraph 1, The above width (W) is 5 to 50 mm, and the thickness (T) is 2 to 20 mm. Copper bear busbar.

13. In paragraph 1, The above copper bare busbar is manufactured by the CONFORM extrusion process. Copper bear busbar.

14. In paragraph 1, The above copper bare busbar is used for electric vehicle battery packs or vehicle power lines. Copper bear busbar.

15. In paragraph 1, The above copper bare busbar is used in the battery pack of the energy storage system. Copper bear busbar.

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