Busbar

Abstract

To provide a busbar capable of accurately blowing a fuse for protecting the circuit while ensuring the mechanical strength of the fuse.SOLUTION: A fuse 18 is placed between an input terminal 14 and an output terminal 16. In the fuse 18, the cross-sectional area S2 of the current path from the input terminal 14 to the output terminal 16 is the smallest. The fuse 18 has a metal piece 20 with a lower melting point than the busbar base material attached to the fuse 18.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE A bus bar is disclosed herein. [Background technology]

[0002] A bus bar may be used as a conductor that electrically connects a battery and a substrate. For example, Patent Document 1 discloses a bus bar equipped with a fuse portion. The bus bar has a generally flat plate shape. A long hole perpendicular to the current path is drilled in the bus bar. Fuse portions are formed on both ends of the long hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-58731 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a fuse portion is formed on a bus bar to prevent a large current from flowing into a circuit mounted on a board. When a circuit with a low allowable current is mounted, the cross-sectional area of ​​the fuse portion is reduced. However, if the cross-sectional area of ​​the fuse portion becomes too small, the mechanical strength of the fuse portion decreases. For example, there is a risk that the fuse portion may break when vibration is input.

[0005] Therefore, this specification discloses a bus bar having a fuse portion that can be melted with high accuracy to protect a circuit and that has sufficient mechanical strength. [Means for solving the problem]

[0006] Disclosed herein is a busbar. The busbar includes an input terminal, an output terminal, and a fuse portion. The input terminal is connected to a power source. The output terminal is connected to a substrate. The fuse portion is provided between the input terminal and the output terminal. The fuse portion has the smallest cross-sectional area on the current path from the input terminal to the output terminal. Furthermore, a metal piece having a lower melting point than the busbar base material is attached to the fuse portion.

[0007] According to the above configuration, the metal piece is heated and melted. At this time, the fuse portion is hot-dip plated. In the hot-dip plating, an alloy is generated at the boundary between the busbar base material and the molten metal. Since the alloy has a lower melting point than the busbar base material, the fuse portion is more likely to melt. Effect of the Invention

[0008] The bus bar disclosed in this specification can be provided with a fuse portion that can be reliably melted to protect the circuit while also ensuring mechanical strength. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view illustrating a bus bar according to the embodiment, and a battery and a substrate to which the bus bar is connected; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The busbar according to the present embodiment will be described below with reference to the drawings. The shapes, materials, quantities, and values ​​described below are merely examples for the purpose of explanation and can be changed as appropriate according to the specifications of the busbar. In the following, the same reference numerals are used for equivalent elements in all drawings.

[0011] Also, in Figure 1, an orthogonal coordinate system consisting of an X-axis, a Y-axis, and a Z-axis is used. The X-axis indicates the longitudinal direction of the busbar 10. The Y-axis indicates the lateral direction of the busbar 10. The Z-axis indicates the thickness direction of the busbar 10. The X-axis, Y-axis, and Z-axis are mutually orthogonal. Using this orthogonal coordinate system, the position and direction of each component will be explained.

[0012] 1 illustrates a battery 50, a substrate 55, and a bus bar 10. These components are mounted on, for example, a vehicle.

[0013] The busbar 10 is a conductor that electrically connects the battery 50 and the substrate 55. The base material of the busbar 10 is, for example, copper. For example, the busbar 10 is formed by processing a copper plate. Alternatively, a highly conductive alloy such as a Cu-Mg alloy may be used as the base material of the busbar 10. The surface of the busbar 10 may be covered with a Sn plating layer.

[0014] The bus bar 10 includes an input terminal 14, an output terminal 16, a fuse portion 18, and a metal piece 20. The input terminal 14 and the output terminal 16 are disposed at both ends in the longitudinal direction of the bus bar 10. The fuse portion 18 is formed between the input terminal 14 and the output terminal 16.

[0015] The input terminal 14 is connected to, for example, a terminal 52 of a battery 50. The battery 50 is a power source for a circuit mounted on a substrate 55. For example, the terminal 52 of the battery 50 is a protrusion. The input terminal 14 is also an opening into which the terminal 52 is inserted.

[0016] Output terminal 16 is connected to substrate 55. For example, a control circuit is mounted on substrate 55. Furthermore, terminal 57 is provided on the lower surface of substrate 55. For example, output terminal 16 protrudes in the thickness direction from main body 12, which is the flat plate portion of busbar 10. Furthermore, solder 17 is disposed on the upper end of output terminal 16. Terminal 57 of substrate 55 and output terminal 16 are connected via solder 17.

[0017] Among the portions of busbar 10, fuse portion 18 has the smallest cross-sectional area on the current path from input terminal 14 to output terminal 16. For example, busbar 10 is formed to have a cross-sectional area S1 over its entire length excluding fuse portion 18. Furthermore, busbar 10 is formed to have a cross-sectional area S2 over the entire length of fuse portion 18. For example, fuse portion 18 has a rectangular cross section.

[0018] For example, the cross-sectional area S2 of the fuse portion 18 is formed to be less than 20% of the cross-sectional area S1 so that the bus bar 10 can be melted first. Also, in order to ensure the mechanical strength of the fuse portion 18, the cross-sectional area S2 is formed to be 5% or more of the cross-sectional area S1.

[0019] A metal piece 20 is attached to the fuse portion 18. The metal piece 20 has a lower melting point than the base material of the bus bar 10. For example, the metal piece 20 is tin (Sn) solder.

[0020] Metal piece 20 has a sufficient thickness to enable gradual alloy generation, which will be described later. For example, metal piece 20 is disposed as a protrusion on upper surface 18A of fuse portion 18. The protruding height of metal piece 20 is set to be, for example, 30% to 90% of the thickness of fuse portion 18.

[0021] Furthermore, since it is sufficient that only a portion of fuse portion 18 melts down when it is blown, when fuse portion 18 has an elongated shape as shown in Fig. 1, metal piece 20 may be disposed on only a portion of the fuse portion in the longitudinal direction. For example, the length (X-axis dimension) of metal piece 20 may be 5% or more and 20% or less of the overall length of fuse portion 18. Metal piece 20 is disposed, for example, in the center of fuse portion 18 along the longitudinal direction of bus bar 10. Metal piece 20 is also attached to upper surface 18A of fuse portion 18.

[0022] For example, when a large current flows from the battery 50 to the input terminal 14, the fuse portion 18 is heated by Joule heat. This heat also heats the metal piece 20. When the metal piece 20 is heated to its melting point, it begins to melt. The molten metal piece 20 covers the top surface 18A and both side surfaces 18B of the fuse portion 18. In other words, the top surface 18A and both side surfaces 18B of the fuse portion 18 are hot-dip plated.

[0023] It is known that in hot-dip plating, an alloy is formed at the boundary between the base material and the plated material. In general, the melting point (eutectic temperature) of an alloy is lower than that of the base material. Therefore, the generated alloy dissolves before the base material of the fuse portion 18. The base material of the fuse portion 18, which was covered with an alloy layer, comes into contact with the liquid metal piece 20 as the alloy layer melts away. An alloy is then generated at the boundary between the two. The gradual generation of the alloy in this manner promotes the melting of the fuse portion 18. [Explanation of symbols]

[0024] 10 bus bar, 14 input terminal, 16 output terminal, 18 fuse part, 20 metal piece, 50 battery, 55 circuit board.

Claims

[Claim 1] An input terminal connected to a power source; An output terminal connected to the board; a fuse portion provided between the input terminal and the output terminal; A busbar comprising: the fuse portion has the smallest cross-sectional area on a current path from the input terminal to the output terminal, Furthermore, a metal piece having a lower melting point than the base material of the bus bar is attached to the fuse portion. Busbar.

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