Bus bar

Abstract

The bus bar includes a pair of connection portions configured to be connected to a connection object, a conductor portion between the pair of connection portions, and a heat sink protruding from the conductor portion. An area of a cross-section orthogonal to the current path in a first region where the fins are provided is smaller than an area of a cross-section orthogonal to the current path in a second region that is outside the first region and includes the connection portion.

Description

Technical Field

[0001] This disclosure relates to a busbar. Background Technology

[0002] A busbar for connecting terminals of adjacent secondary batteries in a battery pack is known, comprising a plate-shaped base with through holes for terminal insertion and a plurality of heat sinks disposed perpendicular to the base, such as those disclosed in JP2013-105674A. In the busbar described in JP2013-105674A, by providing heat sinks on the base, the area and cross-sectional area of ​​the busbar are increased, and the heat dissipation effect of the busbar is enhanced.

[0003] However, in the busbar described in JP2013-105674A, there is a trade-off between heat dissipation and weight due to the addition of heat sinks at the base. Heat dissipation is enhanced, but weight is also increased.

[0004] In view of the above, the purpose of this disclosure is to provide a busbar that can enhance heat dissipation while suppressing weight increase. Summary of the Invention

[0005] According to this disclosure, the busbar includes: a pair of connecting portions configured to connect to a connected object; a conductor portion located between the pair of connecting portions; and a heat sink protruding from the conductor portion. The area of ​​a cross-section orthogonal to the current path in a first region where the heat sink is disposed is smaller than the area of ​​a cross-section orthogonal to the current path in a second region outside the first region and including the connecting portions.

[0006] According to this disclosure, it is possible to enhance heat dissipation while suppressing weight increase. Attached Figure Description

[0007] Figure 1 This is a perspective view showing a busbar according to an embodiment of the present disclosure;

[0008] Figure 2 It is shown Figure 1 The cross-sectional view of the busbar shown;

[0009] Figure 3 It is shown Figure 1 A three-dimensional view of the connection part of the busbar shown;

[0010] Figure 4 This is a perspective view showing the generatrix according to the first comparative example;

[0011] Figure 5 This is a cross-sectional view of the busbar according to the second comparative example;

[0012] Figure 6 It shows the basis Figure 4A graph showing the simulation results of the saturation temperature of the busbar in the first comparative example;

[0013] Figure 7 It shows the basis Figure 5 A graph showing the simulation results of the saturation temperature of the busbar in the second comparative example;

[0014] Figure 8 It is shown that it has the same as according to Figure 1 A graph showing the simulation results of the saturation temperature of a busbar with the same shape and size as the busbar in the illustrated embodiment, and having a surface without alumina treatment;

[0015] Figure 9 It shows the basis Figure 1 A graph showing the simulation results of the busbar saturation temperature in the illustrated embodiment;

[0016] Figure 10 This is a perspective view showing a busbar according to another embodiment of the present disclosure; and

[0017] Figure 11 It is shown Figure 10 The saturation temperature of the busbar shown and according to Figure 4 The figure shows the simulation results of the saturation temperature of the busbar in the first comparative example. Detailed Implementation

[0018] In the following description, this disclosure will be made with reference to preferred embodiments. This disclosure is not limited to the embodiments shown below, and the embodiments shown below may be suitably modified without departing from the spirit of this disclosure. In the embodiments described below, some constructions may not be described or shown in the drawings, and regarding the details of the omitted techniques, well-known or publicly known techniques will be appropriately applied as long as they do not contradict the following description.

[0019] Figure 1 This is a perspective view showing busbar 1 according to an embodiment of the present disclosure. Figure 1 The busbar 1 shown is a conductor that connects the terminals T of adjacent secondary batteries in a battery pack installed in an electric vehicle, such as an electric car or a hybrid vehicle. When energized, a high voltage and high current flow through the busbar 1. The application of the busbar 1 is not limited to the secondary batteries of electric vehicles, but can also include switchboards, control panels, etc.

[0020] Busbar 1 is an aluminum casting with an alumina-treated surface, and includes a base 11 in the shape of a rectangular plate and a plurality of heat sinks 12 integrally formed with the base 11. The base 11 includes a pair of connecting portions 111 and a conductor portion 112 located between the pair of connecting portions 111. The conductor portion 112 extends between the pair of connecting portions 111, and the connecting portions 111 are respectively provided at the ends of the busbar 1 in the longitudinal direction. In the busbar 1, current flows along the longitudinal direction of the busbar 1. That is, the current path of the busbar 1 extends along the longitudinal direction of the busbar 1.

[0021] The connecting portion 111 is a rectangular plate-shaped portion that contacts the terminal T of the secondary battery, and has a plate thickness that is relatively larger than that of the conductor portion 112. In this embodiment, the plate thickness of the connecting portion 111 is 7 mm, and the width of the connecting portion 111 (the dimension in the direction orthogonal to the current path) is 20 mm. The plate thickness of the connecting portion 111 is preferably 5 mm or more and 10 mm or less, and the width of the connecting portion 111 is preferably 10 mm or more and 30 mm or less.

[0022] Figure 2 It is shown Figure 1 The figure shows a cross-sectional view of busbar 1. This figure shows a cross-section of the middle part of busbar 1 cut along a direction orthogonal to the longitudinal direction (current path) in the longitudinal direction.

[0023] like Figure 2 As shown, the thickness of the conductor portion 112 is relatively small compared to the thickness of the connecting portion 111. Multiple heat sinks 12 protrude from one surface of the conductor portion 112 in a direction perpendicular to that surface. In this embodiment, the thickness of the conductor portion 112 is 3.7 mm, and the width of the conductor portion 112 (the dimension in the direction orthogonal to the current path) is 20 mm. The thickness of the conductor portion 112 is preferably 1 mm or more and 5 mm or less, and the width of the conductor portion 112 is preferably 10 mm or more and 30 mm or less.

[0024] Multiple (three in this embodiment) heat sinks 12 are disposed on one surface of the conductor portion 112, arranged at equal intervals in the width direction of the surface (the direction orthogonal to the current path), and extending along the longitudinal direction of the surface. Figure 1 As shown, each heat sink 12 is formed as a rectangular plate and extends from the boundary between the conductor portion 112 and one connecting portion 111 to the boundary between the conductor portion 112 and another connecting portion 111. In this embodiment, the height (width) of the heat sink 12 is 20 mm, and the plate thickness of each heat sink 12 is 3.7 mm. The height of each heat sink 12 is preferably 10 mm or more and 30 mm or less, and the plate thickness of each heat sink 12 is preferably 1 mm or more and 5 mm or less.

[0025] A step is formed at the boundary between one surface of the conductor portion 112 and one surface of the connecting portion 111, and the other surface of the conductor portion 112 and the other surface of the connecting portion 111 are flush without a step. The other surface of the connecting portion 111 is flush with the terminal T (see...). Figure 1 A surface contact.

[0026] In this embodiment, terminal T is a female terminal, and a screw hole (not shown) for fastening a bolt (not shown) is formed in terminal T. Correspondingly, a through hole 111A for bolt insertion is formed in the connecting portion 111, thereby fastening the connecting portion 111 and terminal T by bolt. When terminal T is a male terminal, a bolt (not shown) protruding from terminal T is inserted into the through hole 111A, and the connecting portion 111 and terminal T are fastened by bolt and nut (not shown).

[0027] Here, the cross-sectional area (hereinafter referred to as cross-sectional area) of busbar 1 in the direction orthogonal to the current path is different between the first region A1 where the heat sink 12 is provided and the second region A2 where the heat sink 12 is not provided. The cross-sectional area of ​​the first region A1 is smaller than that of the second region A2. In this embodiment, the region formed by the conductor portion 112 and the heat sink 12 is the first region A1, while the region formed only by the connecting portion 111 is the second region A2.

[0028] In this embodiment, the cross-sectional area of ​​the first region A1 is 100 mm². 2 The cross-sectional area of ​​the second region A2 is 140 mm². 2 The cross-sectional area of ​​the first region A1 is the sum of the cross-sectional area of ​​the conductor portion 112 and the cross-sectional area of ​​the heat sink 12.

[0029] Figure 3 It is shown Figure 1 The diagram shows a perspective view of the connection portion 111 of the busbar 1. Here, the other surface of the connection portion 111 is the surface that contacts the terminal T (hereinafter referred to as the contact surface) 111B, and the contact surface 111B is not treated with aluminum oxide. This ensures conductivity between the contact surface 111B of the connection portion 111 and the terminal T. On the other hand, the entire surface of the connection portion 111 except for the contact surface 111B, the entire surface of the conductor portion 112, and the entire surface of each heat sink 12 are treated with aluminum oxide. This ensures the insulation of the surfaces of the busbar 1 except for the contact surface 111B. Furthermore, due to the increased emissivity of the surface of the busbar 1, the effect of natural cooling caused by radiation (cooling in a windless state without external wind) is enhanced.

[0030] Here, according to the Stefan-Boltzmann law, the heat dissipated by radiation is defined by the following formula (1). According to the Stefan-Boltzmann law, the higher the emissivity, the better the heat dissipation effect of radiation.

[0031] [Mathematics 1]

[0032] Q = 5.67 × 10 -8 ∈T 4 …(1)

[0033] Where Q is the heat dissipation [W / m] 2 ], ε is emissivity, and T is temperature [K].

[0034] Generally, metals have low emissivity ε and it is difficult to enhance heat dissipation through radiation. Therefore, in this embodiment, the busbar 1 is an aluminum casting, and the area is increased by the heat sink 12. In addition, the entire surface of the busbar 1, except for the contact surface 111B, is treated with aluminum oxide, thereby increasing the emissivity ε and enhancing the heat dissipation effect brought about by radiation.

[0035] Figure 4 This is a perspective view showing the busbar 1' according to the first comparative example. As shown in the figure, the busbar 1' according to the first comparative example is a plate-shaped conductor with a uniform plate thickness and without heat sink 12. The busbar 1' is a long rectangular conductor with a plate thickness of 7 mm and a width of 20 mm, and is an aluminum casting as described in the above embodiment. The cross-sectional area of ​​the busbar 1' is 140 mm². 2 According to the first comparative example, the surface of busbar 1′ is not treated with alumina.

[0036] Figure 5 This is a cross-sectional view of the busbar 1" according to the second comparative example. As shown, the busbar 1" according to the second comparative example is an aluminum casting comprising a rectangular plate-shaped base 11" having a uniform plate thickness and a plurality of heat sinks 12 disposed on one surface of the base 11". Similar to the embodiment described above, the plurality of heat sinks 12 are arranged in parallel at equal intervals in the width direction of one surface of the base 11" and extend along the longitudinal direction of that surface. The plate thickness of the base 11" is 7 mm, the width of the base 11" is 20 mm, the height of the heat sinks 12 is 20 mm, and the plate thickness of the heat sinks 12 is 3.7 mm. The surface of the busbar 1" according to the second comparative example is not treated with aluminum oxide.

[0037] Figure 6 It shows the basis Figure 4 The figure shows the simulation results of the saturation temperature (temperature under thermal saturation) of the busbar 1′ of the first comparative example. Figure 7 It shows the basis Figure 5 The figure shows the simulation results of the saturation temperature of the second comparative example, bus 1". Figure 8 It is shown that it has the same as according to Figure 1 A graph showing the simulation results of the saturation temperature of busbar 1A, which has the same shape and size as busbar 1 in the embodiment shown, and has a surface without alumina treatment.

[0038] exist Figures 6 to 8 In the simulation shown, the saturation temperature of a 450A current flowing through busbars 1′, 1″, and 1A in an environment with an air temperature of 20°C was analyzed using Ansys Icepak, a software used for cooling electronic components. Figures 6 to 8 In this context, temperature is expressed as concentration. The higher the temperature, the higher the concentration.

[0039] according to Figure 6 The simulation results shown confirm that the saturation temperature of busbar 1′ according to the first comparative example is 149.6℃. Figure 7 The simulation results shown confirm that the saturation temperature of busbar 1" according to the second comparative example is 107.9°C. Furthermore, according to... Figure 8 The simulation results shown confirm the results based on... Figure 1 The busbar 1 of the illustrated embodiment has the same shape and size and is not treated with alumina. The saturation temperature of the busbar 1A is 131.7°C, which is about 18°C ​​lower than that of the busbar 1′ according to the first comparative example.

[0040] Here, according to Figure 1 The cross-sectional area of ​​busbar 1 in the embodiment shown is 100 mm². 2 Compared to the cross-sectional area of ​​the generatrix 1′ in the first comparative example (140 mm²), 2 Approximately 30%. Therefore, according to Figure 6 and Figure 8 The simulation results shown confirm that, compared with busbar 1′ according to the first comparative example, busbar 1A, which has the same shape and size as busbar 1 according to the embodiment and is not treated with alumina, can achieve a weight reduction of about 30% and a saturation temperature reduction of about 18°C.

[0041] Figure 9 It shows the basis Figure 1 A graph showing the simulation results of the saturation temperature of busbar 1 in the illustrated embodiment. Figure 9 In the simulation, cooling simulation software for electronic components was used to analyze the saturation temperature of bus 1 when a current of 450A flows through it in an environment with an air temperature of 20°C. Figure 9 In this context, temperature is expressed as concentration. The higher the temperature, the higher the concentration.

[0042] exist Figure 9 In the simulation shown, the saturation temperature of busbar 1, whose entire surface except for contact surface 111B was treated with alumina, was analyzed. Figure 9 In the simulation shown, the emissivity ε of bus 1 is set to 0.9. In this respect, Figure 8 In the simulation shown, the emissivity ε of bus 1A was set to 0.04. Besides the emissivity ε, Figure 8and Figure 9 The simulation conditions shown are the same.

[0043] according to Figure 9 The simulation results shown confirm that the saturation temperature of busbar 1, whose entire surface except for contact surface 111B has been treated with alumina, is 91.2℃. According to... Figure 8 and Figure 9 The simulation results shown confirm that by treating the entire surface except for the contact surface 111B with alumina to increase the emissivity ε, the saturation temperature is reduced by approximately 40°C.

[0044] As described above, in the busbar 1 according to this embodiment, the area of ​​the cross-section orthogonal to the current path in the first region A1 where the heat sink 12 is provided is smaller than the area of ​​the cross-section orthogonal to the current path in the second region A2 outside the first region A1 and including the connecting portion 111. Therefore, by increasing the surface area of ​​the heat sink 12 while reducing the weight increase of the busbar 1, the heat dissipation effect of the busbar 1 can be improved.

[0045] In the busbar 1 according to this embodiment, a pair of connecting portions 111, conductor portions 112, and heat sink 12 are made of aluminum, and the surfaces of conductor portions 112 and heat sink 12 are treated with aluminum oxide. Therefore, in addition to increasing the surface area of ​​the heat sink 12, the emissivity ε of the busbar 1 can be increased, thereby further improving the heat dissipation effect of the busbar 1.

[0046] In the busbar 1 according to this embodiment, except for the contact surface 111B with the terminal T, the surfaces of the pair of connecting portions 111 are treated with aluminum oxide. Therefore, while ensuring the continuity between the busbar 1 and the terminal T, the emissivity ε of the busbar 1 can be increased.

[0047] In the busbar 1 according to this embodiment, a pair of connecting portions 111 and conductor portions 112 are formed in the shape of plates, and the plate thickness of conductor portions 112 is less than the plate thickness of the pair of connecting portions 111. Therefore, the cross-sectional area of ​​conductor portions 112 in the direction orthogonal to the current path is less than the cross-sectional area of ​​the pair of connecting portions 111 in the direction orthogonal to the current path, and the weight of busbar 1 is reduced.

[0048] Figure 10 This is a perspective view showing a busbar 2 according to another embodiment of the present disclosure. The busbar 2 shown in this figure and according to... Figure 1 The busbar 1 in the illustrated embodiment differs in the construction of the connecting portions 211 and 111. Compared to... Figure 1 The components shown in the above embodiments are represented by the same reference numerals and are incorporated herein by reference. Figure 1 The foregoing embodiments are described in the illustration.

[0049] like Figure 10As shown, in the busbar 2 according to this embodiment, the connecting portion 211 is formed in a U-shape. The connecting portion 211 includes a pair of connecting portions 111 and a connecting portion 211B that joins the pair of connecting portions 111. The pair of connecting portions 111 are opposite to each other.

[0050] Terminal T is inserted between the pair of connecting parts 111 and assembled onto the pair of connecting parts 111. A through hole (not shown) is formed in terminal T for inserting a bolt (not shown), and connecting parts 211 and terminal T are fastened by bolts inserted into the through hole 111A and the through hole of terminal T, and nuts (not shown) threadedly connected to the bolts.

[0051] The thickness of the connecting portion 111 is greater than the thickness of the conductor portion 112. Furthermore, the contact surface between the connecting portion 111 and the terminal T is not treated with aluminum oxide, while the entire surface of the busbar 2, except for the contact surface with the terminal T, is treated with aluminum oxide.

[0052] Figure 11 It is shown Figure 10 The temperature of busbar 2 shown and according to Figure 4 The figure shows the simulation results of the temperature of bus 1′ in the first comparative example. In the simulation, the temperature was analyzed by using cooling simulation software for electronic components when an 800A current was passed through bus 2 and 1′ for 1200 seconds in an environment with an air temperature of 20°C.

[0053] according to Figure 11 The simulation results shown confirm that Figure 10 The busbar 2 shown has a ratio according to Figure 4 The first comparative example shown has a higher temperature suppression effect on bus 1′.

[0054] The present disclosure has been described above based on the above embodiments, but the present disclosure is not limited to the above embodiments, and modifications can be made to the above embodiments, and well-known or publicly known technologies can be appropriately combined without departing from the spirit of the present disclosure.

[0055] For example, in the above embodiment, the first region A1 where the heat sink 12 is provided is the region that includes the entire conductor portion 112. Alternatively, the conductor portion 112 may have a region where the heat sink 12 is not provided. In the above embodiment, the second region A2, which includes the connection portion 111 outside the first region A1, is defined as the region of the connection portion 111. Alternatively, a portion of the conductor portion 112 may be included in the second region A2.

Claims

1. A busbar, comprising: A pair of connectors are configured to connect to the connected object; The conductor portion is located between the pair of connecting portions; as well as Heat sink protrudes from the conductor portion. Wherein, the area of ​​the cross section orthogonal to the current path in the first region where the heat sink is provided is smaller than the area of ​​the cross section orthogonal to the current path in the second region outside the first region and including the connection portion.

2. The busbar according to claim 1, in, The pair of connecting parts, the conductor part, and the heat sink are made of aluminum, and The surfaces of the conductor and the heat sink are treated with aluminum oxide.

3. The busbar according to claim 2, in, The surfaces of the pair of connecting parts, excluding the contact surface with the connecting object, are treated with aluminum oxide.

4. The busbar according to claim 1 or 2, in, The pair of connecting portions and the conductor portion are formed in a plate shape, and The thickness of the conductor portion is less than the thickness of the pair of connecting portions.

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