Bus bar and shielded electric wire

Abstract

To provide a bus bar and a shielded electric wire that are capable of enhancing heat dissipation efficiency without increasing the weight.SOLUTION: A bus bar (10) is provided with a conductor layer (11), an insulator layer (13) covering the outer periphery of the conductor layer (11), and a shield layer (15) covering the outer periphery of the insulator layer (13). The thermal conductivity of the insulator layer (13) is 0.2 [W / (m k)] or more.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a bus bar and a shielded wire. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a shielded electric wire arranged in a vehicle uses a bus bar having three layers, that is, a conductor layer, an insulating layer, and a shielding layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 188438 Summary of the Invention [Problem to be solved by the invention]

[0004] When the shielded electric wire described in Patent Document 1 is used as a wiring material for passing current through the drive system of an electric vehicle, the heat generation in the conductor layer is greater due to the large current flowing through the bus bar compared to when the shielded electric wire is used as a wiring material for distributing current from a low-voltage power source to auxiliary devices on the vehicle. However, it is difficult to say that the heat generation efficiency of the shielded electric wire described in Patent Document 1 has been fully considered in consideration of the material properties of the insulator layer and the shield layer.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a bus bar and a shielded wire that can ensure sufficient heat dissipation efficiency even when a large current flows through a conductor layer. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a bus bar and a shielded wire according to the present invention have the following features.

[0007] A bus bar including a conductor layer, an insulator layer covering an outer periphery of the conductor layer, and a shield layer covering an outer periphery of the insulator layer, The thermal conductivity of the insulating layer is 0.2 [W / m·k] or more.

[0008] A shielded wire formed using the above bus bar. Effect of the Invention

[0009] According to the present invention, it is possible to provide a bus bar and a shielded wire that can improve heat dissipation efficiency without increasing the overall weight.

[0010] The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following description of the preferred embodiment of the present invention (hereinafter, referred to as "embodiment") with reference to the accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a bus bar according to an embodiment. [Diagram 2] FIG. 2 is a graph showing the change in conductor temperature for each thermal conductivity of the insulator layer. [Diagram 3] FIG. 3 is a graph showing the change in conductor temperature for each emissivity of the shield layer. [Figure 4] FIG. 4 is a graph showing the change in conductor temperature when the thermal conductivity and emissivity are adjusted simultaneously. [Diagram 5] FIG. 5 is a graph showing the change in conductor temperature for each diameter of the conductor layer. [Figure 6] FIG. 6 is a graph showing the relationship between the thermal conductivity of the insulator layer and the conductor temperature for each thickness of the insulator layer when the thickness of the shield layer is 0.5 mm. [Figure 7] FIG. 7 is a graph showing the relationship between the thermal conductivity of the insulator layer and the conductor temperature for each thickness of the insulator layer when the thickness of the shield layer is 1.0 mm. [Figure 8]FIG. 8 is a graph showing the relationship between the thermal conductivity of the insulator layer and the conductor temperature for each thickness of the insulator layer when the thickness of the shield layer is 1.5 mm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0013] FIG. 1 is a schematic diagram showing the configuration of a bus bar 10 in this embodiment. 1, a busbar 10 in this embodiment is composed of a conductor layer 11 having a circular cross section, an insulator layer 13 covering the outer periphery of the conductor layer 11, and a shield layer 15 covering the outer periphery of the insulator layer. As an example, the busbar 10 constitutes a part of a shielded electric wire W having connectors on both ends.

[0014] In this embodiment, the conductor layer 11 and the shield layer 15 are made of aluminum, and the insulator layer 13 is made of polyethylene. The conductor layer 11 and the shield layer 15 may be made of another conductor such as copper.

[0015] The insulator layer 13 functions as a covering material for the conductor layer 11. As described later, the insulator layer 13 may be made of a material other than polyethylene as long as it has a predetermined thermal conductivity. In addition, if the material constituting the insulator layer 13 contains a phase transition material (PCM), the insulator layer 13 is softened by heat generation from the conductor layer 11 and adheres closely to the conductor layer 11, which is preferable because it increases the heat dissipation efficiency of the conductor layer 11.

[0016] Heat generated in the conductor layer 11 due to a current flowing through the busbar 10 is thermally conducted by the insulator layer 13 and the shield layer 15, and is dissipated by radiation from the surface of the shield layer 15. Heat dissipation by radiation is defined by the Stefan-Boltzmann law. Q=5.67*10 -8 εT 4 Here, Q is the amount of heat radiated [W / m2 ], ε represents emissivity, and T represents temperature [K].

[0017] According to the Stefan-Boltzmann law, the higher the emissivity, the greater the radiation effect due to radiation. Methods for increasing the emissivity of the shield layer 15 include oxidizing the surface of the shield layer 15, applying a paint that increases the emissivity to the surface, coating the surface with a sufficiently thin resin, roughening the surface, and the like.

[0018] FIG. 2 is a graph showing the change in conductor temperature for each thermal conductivity of the insulator layer 13. In FIG. In the following analysis, the conductor layer 11 has a circular cross section of 95 mm 2 It is assumed that the busbar 10 has a cross-sectional area of ​​50 [mm] and a current of 500 [A] is continuously passed through the conductor layer 11 for one hour. When the shielded wire W and the busbar 10 are actually installed in a vehicle, their lengths are set to any length depending on the purpose, but in the analysis, the cross-sectional area and cross-sectional shape are constant, so they may be any length. In this analysis, the busbar 10 has a length of 50 [mm]. The thickness of the insulator layer is set to 1.5 [mm], and the thickness of the shield layer 15 is set to 1.0 [mm].

[0019] 2, the solid line 21 indicates the case of the resin according to the present embodiment, in which the thermal conductivity of the insulator layer 13 is 0.33 [W / m·K], the dashed line 22 indicates the case of 1.0 [W / m·K], which is assumed to be a resin with a relatively low thermal conductivity among high thermal conductive resins, the dashed line 23 indicates the case of 3.0 [W / m·K], which is assumed to be a general high thermal conductive resin, the dashed line 24 indicates the case of 20.0 [W / m·K], which is assumed to be a resin with the upper limit of thermal conductivity among high thermal conductive resins, and the dotted line 25 indicates the case of 0.17 [W / m·K], which is assumed to be a general resin. Note that in all cases, the emissivity of the shield layer 15 is set to the conventional 0.06.

[0020] As shown in the graph in Figure 2, in all cases, the thermal conductivity is higher than that of conventional general resins, and the higher the thermal conductivity, the better the heat dissipation effect. In particular, if the thermal conductivity of the insulator layer 13 is 0.33 [W / m K], it can be seen that the rise in conductor temperature can be sufficiently suppressed without increasing the thickness of the shield layer 15.

[0021] FIG. 3 is a graph showing the change in conductor temperature for each emissivity of the shield layer 15. In FIG. 3, solid line 31 is set to 0.06 assuming that the emissivity of shield layer 15 is that of a non-oxidized metal, dashed line 32 is set to 0.21 assuming that the emissivity of shield layer 15 is that of aluminum oxide, dashed line 33 is set to 0.52 assuming that the emissivity of shield layer 15 is that of copper oxide, and dashed line 34 is set to 0.9 assuming a high-emissivity shield layer 15. In all cases, the thermal conductivity of insulator layer 13 is set to 0.33 [W / m K].

[0022] As shown in the graph of FIG. 3, it can be seen that the higher the emissivity of the shield layer 15, the higher the heat dissipation effect.

[0023] FIG. 4 is a graph showing the change in conductor temperature when the thermal conductivity and emissivity are adjusted simultaneously. In the graph of Figure 4, solid line 41 is for a thermal conductivity of 0.33 [W / m K] and an emissivity of 0.06. Dashed line 42 is for a thermal conductivity of 0.33 [W / m K] and an emissivity of 0.9. Dashed line 43 is for a thermal conductivity of 1.0 [W / m K] and an emissivity of 0.9. Dashed line 44 is for a thermal conductivity of 3.0 [W / m K] and an emissivity of 0.9.

[0024] 4, it can be seen that the temperature of conductor layer 11 can be suppressed by increasing the emissivity of shield layer 15. It can also be seen that even if the thermal conductivity of insulator layer 13 is about 0.33 [W / m K], heat generation in conductor layer 11 can be suppressed depending on the emissivity of shield layer 15.

[0025] The above analysis shows that heat generation in the conductor layer 11 can be suppressed by at least one of increasing the thermal conductivity of the insulator layer 13 and increasing the emissivity of the shield layer 15. Therefore, when the cross-sectional area of ​​the busbar 10 having such a high heat dissipation effect is made smaller than the conventional one, an analysis was performed to find a cross-sectional area that provides the same level of heat dissipation effect as the conventional busbar.

[0026] FIG. 5 is a graph showing the change in conductor temperature for each diameter of the conductor layer. In the graph of FIG. 5, the solid line 51 indicates the thermal conductivity of 0.33 [W / m K] and the cross-sectional area of ​​95 [mm 2 The broken lines 52 to 54 are for a thermal conductivity of 3.0 [W / m K] and an emissivity of 0.9, with a cross-sectional area of ​​95 [mm 2 ], 80 [mm 2 ], 65 [mm 2 ].

[0027] As shown in the graph of FIG. 5, by adjusting the thermal conductivity of the insulator layer 13 and the emissivity of the shield layer 15, the cross-sectional area of ​​the busbar 10 can be reduced to 65 mm 2 ], it is understood that the temperature of the conductor layer 11 can be suppressed.

[0028] FIG. 6 is a graph showing the relationship between the thermal conductivity of the insulator layer 13 and the conductor temperature for each thickness of the insulator layer 13 when the thickness of the shield layer 15 is 0.5 mm. FIG. 7 is a graph showing the relationship between the thermal conductivity of the insulator layer 13 and the conductor temperature for each thickness of the insulator layer 13 when the thickness of the shield layer 15 is 1.0 mm. FIG. 8 is a graph showing the relationship between the thermal conductivity of the insulator layer 13 and the conductor temperature for each thickness of the insulator layer when the thickness of the shield layer 15 is 1.5 mm. In either case, the conductor layer 11 has a cross-sectional area of ​​95 mm 2 ] and a current of 500 [A] is passed through the conductor layer 11.

[0029] As shown in FIG. 6 to FIG. 8, regardless of the thickness of the shield layer 15, when the thermal conductivity of the insulator layer 13 is less than 0.2 [W / m·k], the thicker the insulator layer 13, the higher the temperature of the conductor layer 11. Conversely, when the thermal conductivity is 0.2 [W / m·k] or more, the thinner the insulator layer 13, the higher the temperature of the conductor layer 11. This indicates that in a region where the thermal conductivity of the insulator layer 13 is low, the thicker the insulator layer 13, the more the heat conduction to the outside is hindered, and therefore the higher the temperature of the conductor layer 11. On the other hand, when the thermal conductivity of the insulator layer 13 is high, the thicker the insulator layer 13 and the larger the heat capacity, the lower the temperature of the conductor layer 11. Note that even if the current flowing through the conductor layer 11 is greater than 500 [A], the relationship between the thickness of the insulator layer 13 and the temperature of the conductor layer 11 is reversed when the thermal conductivity of the insulator layer 13 is 0.2 [W / m·k].

[0030] Therefore, by setting the thermal conductivity of the insulator layer 13 to 0.2 [W / m·k] or more, the heat capacity of the insulator layer 13 increases, making it possible to suppress a temperature rise in the conductor layer 11. In particular, when the thickness of the shield layer 15 is determined by a standard, by setting the thermal conductivity to a value of 0.2 [W / m·k] or more, it is possible to suppress a temperature rise in the conductor layer 11 even if the thickness of the shield layer 15 cannot be optimized from the perspective of heat dissipation efficiency.

[0031] The present invention is not limited to the above-described embodiment, and can be appropriately modified, improved, etc. In addition, the material, shape, size, number, arrangement location, etc. of each component in the above-described embodiment are arbitrary as long as the present invention can be achieved, and are not limited.

[0032] Here, the features of the shielded wire and the bus bar according to the above-described embodiment of the present invention will be briefly summarized and listed in the following [1] to [3]. [1] A busbar (10) including a conductor layer (11), an insulator layer (13) covering an outer periphery of the conductor layer (11), and a shield layer (15) covering an outer periphery of the insulator layer (13), The thermal conductivity of the insulator layer (13) is 0.2 [W / m·k] or more. Busbar(10).

[0033] According to the busbar having the configuration described above in [1], it is possible to realize a busbar that can ensure sufficient heat dissipation efficiency even when a large current flows through the conductor layer. Therefore, it is possible to provide a busbar with high radiation efficiency while suppressing an increase in the weight of the busbar as a whole that would be caused by increasing the thickness of the shield layer to increase the emissivity of the shield layer in order to increase the heat dissipation efficiency of the busbar.

[0034] [2] The material forming the insulator layer (13) contains a phase transition material. The bus bar according to [1] above.

[0035] According to the busbar having the configuration [2] above, when the conductor layer is heated by electric current, the insulator layer softens and adheres closely to the outer periphery of the conductor layer, thereby further improving the radiation efficiency from the conductor layer.

[0036] [3] A shielded wire (W) constructed using the bus bar (10) described in [1] or [2] above.

[0037] According to the shielded electric wire having the configuration [3] above, the heat dissipation effect of the bus bar portion can be improved without increasing the weight of the bus bar. Therefore, by using this bus bar for the shielded electric wire, it can be used as an electric wire for large currents without increasing the weight of the entire electric wire. [Explanation of symbols]

[0038] 10 Bus bar 11 Conductor layer 13 Insulator layer 15 Shielding Layer W Shielded Wire

Claims

1. A bus bar including a conductor layer, an insulator layer covering an outer periphery of the conductor layer, and a shield layer covering an outer periphery of the insulator layer, The thermal conductivity of the insulator layer is 0.2 [W / m · k] or more. Bus bar.

2. The material forming the insulator layer contains a phase transition material. The bus bar according to claim 1 .

3. A shielded wire formed by using the bus bar according to claim 1 or 2.

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