Method for manufacturing bus bar, device for manufacturing bus bar, and bus bar

Abstract

Disclosed is a method for manufacturing a bus bar, which has a conductor and a resin layer that is disposed on the surface of the conductor, the method including: a step for heating the conductor; a step for plasma processing the heated conductor with use of a process gas that contains carbon dioxide; and a step for covering the surface of the plasma-processed conductor with a resin layer, the surface being at 160°C to 220°C.

Description

Busbar manufacturing method, busbar manufacturing device, and busbar

[0001] The present invention relates to a busbar manufacturing method, a busbar manufacturing apparatus, and a busbar.

[0002] Conventionally, a battery unit and an inverter mounted on a battery electric vehicle, a hybrid vehicle, or the like are electrically connected by a bus bar. Generally, an on-board bus bar has a conductor and an insulating resin layer disposed on the surface of the conductor. The on-board bus bar is disposed in a limited space around the battery. Therefore, from the viewpoint of routing, the on-board bus bar is bent in the thickness direction (flatwise bend) or the width direction (edgewise bend) (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a busbar member (busbar) having a busbar (conductor), a first coating (resin layer) that covers a portion of the busbar, and a second coating (resin layer) that covers at least another portion of the busbar. In the busbar member described in Patent Document 1, the surfaces of the straight portions of the busbar are covered with the first coating, the surfaces of the bent portions are covered with the second coating, and the first and second coatings partially overlap each other.

[0004] The busbar member is bent after the surface of the busbar is covered with the first and second covering portions. Because the first and second covering portions overlap, the bending process deforms the second covering portion, but the bending process has little effect on the first covering portion.

[0005] Japanese Patent Application Laid-Open No. 2022-167282

[0006] In the busbar member described in Patent Document 1, the second coating portion on the outside of the bent portion may crack. Furthermore, the second coating portion on the inside of the bent portion may peel off and bulge. These cracks and bulges not only impair the appearance of the busbar member, but also may cause a short circuit.

[0007] Therefore, an object of the present invention is to provide a busbar manufacturing method and apparatus that can manufacture a busbar that maintains adhesion between the conductor and the resin layer even after bending, and a busbar manufactured by these methods.

[0008] In order to solve the above-mentioned problems, one aspect of the present invention provides a method for manufacturing a busbar having a conductor and a resin layer disposed on a surface of the conductor, the method comprising the steps of: heating the conductor; plasma-treating the heated conductor with a process gas containing carbon dioxide; and coating the plasma-treated surface of the conductor, the surface being at a temperature of 160 to 220°C, with a resin layer.

[0009] In order to solve the above-mentioned problems, one aspect of the present invention provides an apparatus for manufacturing a bus bar having a conductor and a resin layer disposed on a surface of the conductor, the apparatus comprising: a heating unit for heating the conductor; a plasma processing unit for plasma-treating the heated conductor with a process gas containing carbon dioxide; and a coating unit for coating the plasma-treated surface of the conductor, the surface being at a temperature of 160 to 220°C, with a resin layer.

[0010] In order to solve the above-described problems, one aspect of the present invention provides an in-vehicle busbar, comprising: a conductor; and a resin layer disposed on a surface of the conductor, wherein the adhesive strength between the conductor and the resin layer is within a range of 1.0 to 6.5 N / mm.

[0011] According to the present invention, a bus bar is provided that can maintain adhesion between the conductor and the resin layer even after bending.

[0012] Fig. 1 is a diagram showing the configuration of a bus bar manufacturing apparatus according to an embodiment of the present invention, and Fig. 2 is a flowchart of a bus bar manufacturing method according to an embodiment of the present invention.

[0013] Hereinafter, a busbar manufacturing method, a busbar manufacturing apparatus, and a busbar according to an embodiment of the present invention will be described with reference to the accompanying drawings. A busbar manufactured by the busbar manufacturing method or busbar manufacturing apparatus according to an embodiment of the present invention is used, for example, to electrically connect an on-board battery and an inverter. In this specification, the upper and lower limits of a numerical range indicated by "to" are included in the numerical range.

[0014] Busbar Manufacturing Apparatus FIG. 1 is a schematic diagram of a busbar manufacturing apparatus 10 for manufacturing a busbar 110 .

[0015] 1 , the manufacturing apparatus 10 for the bus bar 110 includes a heating unit 30, a plasma treatment unit 40, and a covering unit 50. In addition to the above configuration, the manufacturing apparatus 10 for the bus bar 110 of this embodiment also includes a feeding unit 20, a cooling unit 60, a take-up unit 80, and a winding unit 90.

[0016] The unwinding unit 20 unwinds the conductor 100 wound around the first drum 21. The conductor 100 is not particularly limited as long as it can carry a large amount of current. Examples of the conductor 100 include copper, aluminum, and brass. The shape of the conductor 100 is also not particularly limited. In this embodiment, the conductor 100 has a long, thin ribbon shape.

[0017] The heating unit 30 heats the conductor 100 to about 150 to 210°C. A first guide roll 25 is arranged between the unwinding unit 20 and the heating unit 30 to guide the conductor 100 from the unwinding unit 20 to the heating unit 30. The number of heating units 30 is appropriately set depending on the speed at which the conductor 100 is fed and the temperature to be reached by heating. The number of heating units 30 may be one or more. The heating unit 30 may be configured to blow heated air onto the preheated conductor 100, may be configured to bring a known heat source into contact with the preheated conductor 100, or may be configured to use radiant heat.

[0018] The plasma processing unit 40 plasma-treats the heated conductor 100. Plasma-treating the heated conductor 100 improves the adhesion strength between the conductor 100 and the resin layer 120. The plasma processing unit 40 may be configured to perform the plasma treatment under vacuum or atmospheric pressure. The plasma treatment is preferably performed under atmospheric pressure. The process gas used for the plasma treatment is not particularly limited as long as it contains carbon dioxide. For example, the process gas may be air or carbon dioxide. Carbon dioxide gas is preferred as the process gas from the viewpoint of improving the adhesion between the conductor 100 and the resin layer 120. The plasma treatment conditions are an applied voltage of 280 to 300 V, a treatment time of several tens of microseconds, and a process gas flow rate of 20 L / min. When the temperature of the conductor 100 after the heating process and plasma treatment is within the range of 160 to 220°C, the adhesion between the conductor 100 and the resin layer 120 is improved.

[0019] The covering portion 50 forms the busbar 110 by disposing a resin layer 120 on the surface of the plasma-treated conductor 100. The configuration of the covering portion 50 is not particularly limited as long as it can perform the above-mentioned function. For example, the covering portion 50 covers the surface of the conductor 100 with the resin layer 120 by extruding molten resin through a die hole while feeding the conductor 100 from the center of the die hole. Examples of resins that can form the resin layer 120 include polyvinyl chloride, polymethyl methacrylate resin, polypropylene, polyethylene, polyamide, polyacetal, and polycarbonate. From the viewpoint of adhesion between the conductor 100 and the resin layer 120, polyamide 12 is preferred.

[0020] The cooling unit 60 cools the bus bar 110 (the conductor 100 coated with the resin layer 120). The number of cooling units 60 is set appropriately depending on the speed at which the conductor 100 is fed and the set temperature after cooling. The number of cooling units 60 may be one or more. The configuration of the cooling unit 60 is not particularly limited as long as it can appropriately cool the bus bar 110 (the conductor 100 and the resin layer 120). The cooling unit 60 may be configured as an air wiper for air cooling or as a refrigerant tank for cooling with a refrigerant.

[0021] The take-up unit 80 moves the bus bar 110 from the upstream side to the downstream side. The configuration of the take-up unit 80 is not particularly limited as long as it can perform the above-mentioned function. In the present embodiment, the take-up unit 80 has a pair of caterpillars 81, 81. The bus bar 110 is sandwiched between the pair of caterpillars 81, 81. The pair of caterpillars 81, 81 operate to move the bus bar 110 from the upstream side to the downstream side, so that the bus bar 110 moves continuously from the upstream side to the downstream side.

[0022] The winding unit 90 winds up the bus bar 110. In the present embodiment, the winding unit 90 rotates the second drum 91 to wind up the bus bar 110.

[0023] [Busbar Manufacturing Method] Next, a method for manufacturing the busbar 110 will be described. The method for manufacturing the busbar 110 of this embodiment can be performed, for example, by the busbar manufacturing apparatus 10 described above, but may also be performed by other manufacturing apparatuses. Figure 2 is a flowchart of the method for manufacturing the busbar 110.

[0024] As shown in FIG. 2, the method for manufacturing bus bar 110 includes a heating step (S110), a plasma treatment step (S120), a coating step (S130), and a cooling step (S140).

[0025] In the heating step (S110), the conductor 100 is heated to about 150 to 210° C. in order to improve the adhesive strength between the conductor 100 and the resin layer 120. The method for heating the conductor 100 is not particularly limited as long as it can heat the conductor 100 to a predetermined temperature. Examples of methods for heating the conductor 100 include a method of blowing heated air onto the conductor 100, a method of bringing a known heat source into contact with the conductor 100, and a method using radiant heat.

[0026] In the plasma treatment step (S120), the heated conductor 100 is plasma treated to improve the adhesive strength between the conductor 100 and the resin layer 120. The plasma treatment may be performed under vacuum or atmospheric pressure. The plasma treatment is preferably performed under atmospheric pressure. The process gas used for the plasma treatment is not particularly limited as long as it contains carbon dioxide, and may be, for example, air or carbon dioxide. From the viewpoint of improving the adhesiveness between the conductor 100 and the resin layer 120, carbon dioxide gas is preferred as the process gas. After the heating step (S110) and the plasma treatment step (S120), the surface of the conductor 100 is treated to a temperature in the range of 160 to 220°C.

[0027] In the coating step (S130), the plasma-treated surface of conductor 100, which is at 160 to 220° C., is coated with resin layer 120. In this embodiment, for example, coating unit 50 coats the surface of conductor 100 with resin layer 120 by extruding molten resin from a die hole while feeding conductor 100 from the center of the die hole.

[0028] The busbar manufacturing method of this embodiment may further include a cooling step (S140). In the cooling step (S140), the busbar 110 is cooled. The method for cooling the busbar 110 is not particularly limited as long as it can cool the busbar 110 to a desired temperature. Examples of the method for cooling the busbar 110 include air cooling and cooling with a refrigerant. In this embodiment, the busbar 110 is configured to be air-cooled and then cooled with a refrigerant.

[0029] [Busbar Configuration] The busbar 110 manufactured by the busbar 110 manufacturing apparatus 10 or the busbar 110 manufacturing method described above includes a conductor 100 and a resin layer 120 disposed on the surface of the conductor 100. As described above, the conductor 100 is heated to a predetermined temperature, plasma-treated using a predetermined process gas, and then the resin layer 120 is formed, thereby improving the adhesion between the conductor 100 and the resin layer 120. In this case, the adhesion strength between the conductor 100 and the resin layer 120 is within a range of 1.0 to 6.5 N / mm, preferably within a range of 1.19 to 6.31 N / mm, more preferably within a range of 2.0 to 4.0 N / mm, and even more preferably within a range of 2.89 to 3.96 N / mm. If the adhesion strength between the conductor 100 and the resin layer 120 is within the above range, cracks and bulges do not occur during bending.

[0030] The adhesion strength between the conductor 100 and the resin layer 120 can be measured, for example, by the following method. First, the resin layer 120 is removed from the edge portion of the bus bar 110. Next, a portion of the resin layer 120 on the front or back surface of the bus bar 110 is peeled off. Next, the peeled portion is pulled in a direction approximately perpendicular to the surface of the bus bar 110 using a tensile tester at a speed of 50 mm / min, and the stress measured when this is done is taken as the adhesion strength.

[0031] (Effects) According to the busbar manufacturing method, busbar manufacturing apparatus, and busbar of the present embodiment, a heated conductor is plasma-treated in a carbon dioxide or air environment, and then the surface is coated with a resin layer at 160 to 220°C. This provides adhesion and bendability, and ultimately allows the conductor to maintain insulation even after bending. This is thought to be because, when the plasma-treated surface of the conductor is in the range of 160 to 220°C, functional groups (carbonyl groups, carboxyl groups, etc.) are easily formed on the conductor surface due to the plasma treatment, thereby exhibiting adhesion and bendability. On the other hand, when the conductor surface is below 160°C, these functional groups are less likely to be formed, and when the conductor surface is above 220°C, an oxide film layer is formed.

[0032] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0033] [Fabrication of Busbar 1] A conductor (20-30 mm wide x 3-5 mm thick) made of rectangular copper was heated to 160°C and then plasma-treated using carbon dioxide gas as the process gas. Other conditions for the plasma treatment were an applied voltage of 280-300 V, a treatment time of several tens of microseconds, and a process gas flow rate of 20 L / min. The surface of the conductor after the plasma treatment was at 170°C. Next, a resin layer of a predetermined thickness was formed on the surface of the conductor using polyamide 12, to obtain busbar 1.

[0034] [Fabrication of Busbars 2 to 16] Busbars 2 to 16 were obtained in the same manner as busbar 1, except that the process gas and conductor surface temperature in the plasma treatment were changed as shown in Table 1.

[0035] [Peel test] A peel test was performed on bus bars 1 to 16 based on the method described above. The adhesion strength between the conductor and the resin layer after the peel test was measured and evaluated according to the following criteria. The evaluation criteria are as follows: Evaluation criteria ⊚: 2.0 N / mm or more and less than 4.0 N / mm ○: 1.0 N / mm or more and less than 2.0 N / mm or 4.0 N / mm or more and less than 6.5 N / mm △: Less than 1.0 N / mm or 6.5 N / mm or more and less than 13.0 N / mm ×: Separation of the conductor and the resin layer is visible to the naked eye

[0036] [Bending test (edgewise bending)] A bending test (edgewise bending) was performed using the same test specimens as in the peel test. The bending test (edgewise bending) was performed multiple times for some types of test specimens. The bending test (edgewise bending) was performed by bending the test specimen 90° in the width direction so that the bending radius was 10 mm. Pass / fail was determined according to the following evaluation criteria. Pass: The test was performed on multiple specimens, and none of them were visually observed to have cracks or blisters in the resin-coated portion. Fail: The test was performed on multiple specimens, and one or more specimens were visually observed to have cracks or blisters in the resin-coated portion.

[0037] The evaluation results of the peel test and bending test (edgewise bending) for bus bars No. 1 to 16 are shown in Table 1.

[0038]

[0039] As shown in Table 1, busbars 1 to 6, in which a resin layer was formed on a conductor surface that had been heated and plasma-treated with a process gas containing carbon dioxide and had a temperature of 160 to 220°C, showed good results in adhesion strength and bending tests (edgewise bending). Note that because edgewise bending is more severe than flatwise bending, it is believed that busbars 1 to 6 also showed good results in the flatwise bending test.

[0040] As shown in Table 1, bus bars 13 to 15, which were not plasma treated, had poor adhesion strength and poor results in the bending test (edgewise bending). Bus bars 7 to 12, which were heated to an inappropriate temperature, also had poor adhesion strength and some poor results in the bending test (edgewise bending). Furthermore, bus bar 16, which used nitrogen as the process gas, also had poor adhesion strength.

[0041] The bus bar obtained by the present invention is useful as a bus bar for electrically connecting, for example, between an in-vehicle battery and an inverter.

[0042] REFERENCE SIGNS LIST 10 Manufacturing device 20 Unwinding section 21 First drum 25 First guide roll 30 Heating section 40 Plasma treatment section 50 Covering section 60 Cooling section 65 Second guide roll 80 Take-up section 81 Caterpillar 90 Winding section 91 Second drum 100 Conductor 110 Bus bar 120 Resin layer

Claims

1. A method for manufacturing a busbar having a conductor and a resin layer disposed on a surface of the conductor, comprising the steps of: heating the conductor; plasma-treating the heated conductor with a process gas containing carbon dioxide; and coating the plasma-treated surface of the conductor, the surface being at a temperature of 160 to 220°C, with a resin layer.

2. The method of claim 1, wherein the process gas is carbon dioxide gas.

3. An apparatus for manufacturing a bus bar having a conductor and a resin layer disposed on a surface of the conductor, comprising: a heating unit for heating the conductor; a plasma processing unit for plasma-treating the heated conductor with a process gas containing carbon dioxide; and a coating unit for coating the plasma-treated surface of the conductor, the surface being at a temperature of 160 to 220°C, with a resin layer.

4. A busbar for vehicle use, comprising: a conductor; and a resin layer disposed on a surface of the conductor, wherein the adhesive strength between the conductor and the resin layer is within a range of 1.0 to 6.5 N / mm.

5. The busbar according to claim 4, wherein the adhesive strength between the conductor and the resin layer is within a range of 2.0 to 4.0 N / mm.

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