JP2022090975A - Terminal weld joint and power conversion device - Google Patents

Abstract

To provide a bus bar weld joint that is able to efficiently manage the quality of a weld portion of a bus bar.SOLUTION: In a terminal weld joint and a power conversion device that have a weld joint having a weld structure in which a first member and a second member, which are rectangular plates, are superposed on each other, face to face, and joined, a weld portion that joins the first member and the second member has: a superposed weld portion that reaches the second member from a surface of the first member, which surface is opposite the second member; and a fillet weld portion in which the first member and the second member are welded and joined at least at one end of the first member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a terminal welded joint and a power conversion device.

In power converters (inverters), engine control units, motors, batteries, etc., conductors called bus bars are used to obtain electrical connections. Since this bus bar is required to have conductivity, copper or aluminum is generally used, and TIG (Tungsten Inert Gas) welding is used as the connection method. As a method of joining bus bars by this welding, a worship joint or a lap joint is adopted.

The following Patent Document 1 is known as a background technique of the present invention. In Patent Document 1, among a plurality of AC bus bars 3a, 3b, 3c connected to the semiconductor module 2, some of the AC bus bars 3a, 3b have a thickness at the connecting portion 33, which is thicker than that of the first connecting portion 31. A technique for suppressing a temperature rise of an electronic component by forming a thick thick portion 34 is disclosed.

Japanese Unexamined Patent Publication No. 2015-171243

In the joint method described in Patent Document 1, the quality of the welded portion of the joint cannot be determined from the appearance, and it is difficult to control the quality of the welded portion (thick portion) 34. In view of the above, it is an object of the present invention to provide a bus bar welded joint capable of efficiently controlling the quality of the welded portion of the bus bar.

The terminal welded joint and the power conversion device are welded joints having a welded structure in which a first member and a second member, which are rectangular plates, are superposed on each other and joined to each other. The welded portion that joins the member and the second member includes a lap weld portion that reaches from the surface of the first member opposite to the second member to the second member, and the first member. At least one end of the member has a fillet welded portion to which the first member and the second member are melt-bonded.

According to the present invention, it is possible to provide a bus bar welded joint capable of efficiently controlling the quality of the welded portion of the bus bar.

The figure explaining the terminal welded joint which concerns on 1st Embodiment of this invention. The figure explaining the forming method of the terminal welded joint. FIG. 1A is a cross-sectional view taken along the line AA of FIG. A defective example of the terminal welded joint according to the first embodiment of the present invention. The figure explaining the overlap terminal which concerns on 2nd Embodiment of this invention. FIG. 5 is a diagram showing a terminal welded joint. A defective example of the terminal welded joint according to the second embodiment of the present invention. The figure explaining the inverter which comprises the terminal welded joint of this invention.

(Comparison between the prior art and the present invention)
A joint used in common with the prior art and the present invention will be described. In an inverter device that consists of a power module equipped with a switching element, a smoothing capacitor, a bus bar, a control circuit, etc., and generates alternating current from a DC power source such as a battery, the bus bar is electrically connected to the power module, smoothing capacitor, etc. It is connected to the. Further, the alternating current generated by the power module is supplied to the motor via this bus bar. Conventionally, a joint method called a worship joint has been adopted for the connection between the bus bar and other electronic components by welding.

Since this worship joint is a method of joining with the bus bar in a vertical shape, it has low space efficiency and is a welded joint method that is disadvantageous for miniaturization (shortening of height) and space saving. Therefore, it is required to change from a worship joint to a lap joint for welding the bass bar.

This lap joint is a welded joint method in which bass bars are laid on top of each other and joined, and is excellent in space efficiency. However, since the joint portion of the lap joint is the interface of the lap portion, it is difficult to visually confirm whether or not the weld is performed correctly when the joint portion is viewed from the outside. Therefore, there is a problem in terms of quality control of the welded portion. In this case, it is necessary to guarantee the quality of the welded portion by another inspection process.

Therefore, in the present invention, the welded portion has a lap welded portion and a fillet welded portion, and it is possible to visually confirm from the outside that the fillet welded portion is melted and joined with the lap welded portion. .. By doing so, a separate inspection process is not required as compared with the conventional case, so that the process can be shortened and a Basba welded joint capable of efficiently controlling the quality of the welded portion of the Basba can be realized.

(First Embodiment of the present invention)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the technical idea of the present invention may be realized by combining other known components. In each figure, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

Further, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range and the like disclosed in the drawings.

FIG. 1 is a diagram illustrating a terminal welded joint according to the first embodiment of the present invention.

The terminals 1a and 1b have a rectangular shape, and are arranged so as to be overlapped with each other on the upper and lower surfaces. In this embodiment, the material of the terminals 1a and 1b is pure copper (C1020), the terminal 1a has a width of 7 mm and a thickness of 1 mm, and the terminal 1b has a width of 4 mm and a thickness of 0.5 mm.

The welded portion 2 is formed from one end to the other in the short side direction of the terminal 1b. As a result, the terminals 1a and the terminals 1b that are overlapped with each other are joined to each other. The fillet welded portion 2a is formed by melt-joining the terminals 1a and the ends of the terminals 1b to each other. From this, it can be seen that the terminal 1a and the terminal 1b are in a state of being continuous by the welded portion 2.

FIG. 2 is a diagram illustrating a method of forming a terminal welded joint.

The welding equipment for obtaining the welded portion 2 of the present invention includes a shield gas nozzle 11, a laser processing head 13, a laser oscillator 14, an optical fiber 15, and an XY stage 16.

The laser 10 generated by the laser oscillator 14 is irradiated to the terminals 1a and 1b on the XY stage through the optical fiber 15 and the laser processing head 13. The laser 10 is irradiated to one end side of the terminal 1b, and the XY stage operates to the right in FIG. 2 during the laser irradiation, so that one end of the terminal 1a and the terminal 1b is melted.

By mixing the molten portions of the terminal 1a and the terminal 1b, the fillet welded portion described above is formed on one side of the terminal 1b. Further, by moving the XY stage 16, the terminals 1a and 1b are melted and mixed, so that the above-mentioned lap welded portion is formed. Further, by moving the XY stage 16, another fillet welded portion is formed on the other side of the terminal 1b. By doing so, a welded portion between the terminal 1a and the terminal 1b is formed.

The laser 10 is a fiber laser having a wavelength of 1070 nm, and argon gas is used as the shield gas 12 emitted from the shield gas nozzle, but the laser 10 is not limited to this. Similarly, although welding is performed using the laser 10 as a heat source, the welding is not limited to the laser. Further, although the XY stage 16 is moved in a straight line to form the welded portion 2 having a linear shape, the welded portion 2 may be formed in a circular shape.

FIG. 3 is a cross-sectional view taken along the line AA of FIG.

Both ends of the lap welded portion 3 are fillet welded portions 2a. It can be confirmed that the fillet welded portion 2a is in a state of being metal-bonded to the terminal 1a. Further, it can be confirmed that all the terminals 1b described above are melted and become a part of the lap welded portion 3 and are metal-bonded to the terminals 1a. As a result, the terminals 1a and 1b are substantially melt-bonded.

The boundary between the lap weld 3 and the fillet weld 2a is defined by the end face of the terminal 1b (FIG. 1). Considering this boundary as a reference, the width of the formed fillet welded portion 2a is smaller than the width of the lap welded portion 3. By confirming this, it is possible to confirm whether or not the metal joint between the fillet welded portion 2a and the lap welded portion 3 has continuity, and also confirm whether or not the welding equipment (FIG. 2) is operating normally. ..

FIG. 4 is a defective example of the terminal welded joint according to the first embodiment of the present invention.

If the laser output is small, poor penetration of the welded portion 2 may occur. In FIG. 4, when the terminals 1a and the ends of the terminals 1b are melted, the amount of melting is insufficient and they are not mixed with each other. As a result, the fillet welded portion is not formed, and the welded portion 2 of the terminal 1a and the terminal 1b is separated without being melt-bonded. Further, although the welded portion 2 of the terminal 1b is melted, it does not melt to the terminal 1a due to the small laser output, and it is not possible to form a lap welded portion that reaches from the terminal 1b to the terminal 1a and is welded.

As described above, the melting behavior of the fillet welded portion and the lap welded portion are the same, and if the fillet welded portion is not melted, it can be seen that the lap welded portion is not melted either. Therefore, the quality of the lap weld can be estimated by evaluating the performance of the fillet weld.

(Second embodiment)
FIG. 5 is a diagram illustrating stacked terminals according to a second embodiment of the present invention. FIG. 5A shows a perspective view of the object to be welded, and FIG. 5B shows a cross-sectional view thereof.

In the present embodiment, the terminal 1bA has a slit 27 which is an opening. The material of the terminal 1bA and the terminal 1aA is pure copper (C1020) as in the first embodiment, the terminal 1bA has a width of 12 mm and a thickness of 1 mm, and the terminal 1aA has a width of 12 mm and a thickness of 2 mm. Further, the shape of the slit 27 of the terminal 1bA is a rectangle with rounded corners, and is a through slit 27 having a length of 6 mm and a width of 3 mm.

FIG. 6 is a diagram in which a terminal welded joint is formed in FIG. FIG. 5A shows a perspective view of the object to be welded, and FIG. 5B shows a cross-sectional view thereof.

In the welded portion 2A, two welded portions are formed so as to straddle the slits 27. By irradiating the laser 10 (FIG. 2) from one end of the terminal 1bA, the end of the terminal 1bA and the terminal 1aA are melted and mixed. As a result, the fillet welded portion 2aA of the terminal 1bA (end portion) and the terminal 1aA is formed on one of the slits 27. Further, by moving the XY stage 16 (FIG. 2), the terminal 1bA and the terminal 1aA are melted and mixed to form a lap welded portion 3A which reaches from the terminal 1bA to the terminal 1aA and is welded. ..

Further, when the laser 10 reaches the other end of the slit 27 of the terminal 1bA, the end portion of the terminal 1bA and the terminal 1aA melt and mix with each other, so that the other end of the slit 27 has the terminal 1bA (end portion) and the terminal. The fillet welded portion 2aA of 1aA is formed. In the present embodiment, when the vertical cross section of the welded portion 2A is confirmed, it can be seen that the fillet welded portion 2aA and the lap welded portion 3A have a metallic bond.

FIG. 7 is a defective example of the terminal welded joint according to the second embodiment of the present invention.

The molten portion 2A of the terminal 1bA and the terminal 1aA is in a state where the fillet welded portion 2aA described above cannot be formed due to poor melting due to a small laser output or the like. As described above, the end portion of the slit 27 of the terminal 1bA and the terminal 1aA are melted by the laser irradiation, but the amount of melting is insufficient and they are not mixed. As a result, the fillet welded portion 2aA was not formed. Further, although the terminal 1bA was melted, it reached the terminal 1aA and did not melt due to insufficient laser output, and the lap welded portion 3A could not be formed as shown in FIG.

As described above, even in the welded joint having the slit 27, it can be confirmed that the melting behaviors of the fillet welded portion 2aA and the lap welded portion 3A are the same. Therefore, as in the first embodiment, the lap welded portion 3A is a terminal by confirming whether or not there is continuity of the metal joint between the terminal 1bA (end portion) and the terminal 1aA from the outside of the fillet welded portion 2aA. It can be seen whether or not the welding is performed by reaching the terminal 1aA from 1bA. Therefore, the quality of the welded portion 2A can be estimated by evaluating the performance of the fillet welded portion 2aA.

(Power conversion device that realizes the first and second embodiments)
FIG. 8 is a diagram illustrating an inverter including the terminal welded joint of the present invention.

The inverter 100 includes a capacitor 33, a bus bar 32, and a power module 30 (other parts are omitted). The capacitor 33 and the power module 30 are electrically connected by a bus bar 32.

In the inverter 100, the welded joint of the present invention can be applied to the welding of the bus bar 32 and the capacitor 33, and the welding of the bus bar 32 and the power module 30.

In the welding of the bus bar 32 and the capacitor terminal 34, lap welding in which the bus bar 32 is arranged on the upper side of FIG. 8 is adopted. In this welding, the slit 27 is processed in the bus bar terminal 32a, and the fillet welded portion and the lap welded portion can be formed by laser welding including the slit 27 (second embodiment). See). It is possible to control the quality of the welded portion by checking from the outside whether the fillet welded portion is connected to the lap welded portion.

In the welding of the power module terminal 31 and the bus bar terminal 32b, lap welding in which the bus bar terminal 32b is arranged on the upper side of FIG. 8 is adopted, and lap welding is performed with the fillet welded portion by laser welding from the end of the bus bar 32. A portion can be formed (see first embodiment). Similarly, it is possible to control the quality of the welded portion by checking from the outside whether or not the fillet welded portion is connected to the lap welded portion.

In this way, by facilitating quality control of the lap joint, it becomes easier to adopt it as a joint method at the time of terminal welding, and the space inside the inverter 100 can be used more efficiently than by adopting a configuration such as a worship joint. can do. This can contribute to the miniaturization and reduction of the height of the inverter 100.

According to one embodiment of the present invention described above, the following effects are exhibited.

(1) The terminal welded joint is a welded joint having a welded structure in which a first member and a second member, which are rectangular plates, are superposed on each other and joined to each other, and the first member. The welded portion that joins the second member to the second member is a lap weld portion that reaches from the surface of the first member opposite to the second member to the second member, and the first member. At at least one end of the above, there is a fillet welded portion to which the first member and the second member are melt-bonded. By doing so, it is possible to provide a Basba welded joint capable of efficiently controlling the quality of the welded portion of the Basba.

(2) The fillet weld is formed on the edge of the opening of the first member. By doing so, it is possible to control the quality of the entire welded portion from the fillet welded portion even in the terminal having a slit.

(3) The first member and the second member on which the terminal welded joint is formed are mainly composed of copper or aluminum. By doing so, metal bonding between the terminals can be performed.

(4) The width of the lap weld is larger than the width of the fillet weld. By doing so, it is possible to confirm the continuity of the metal joint between the fillet welded portion and the lap welded portion and to confirm whether or not the welding equipment is operating normally.

(5) A power conversion device (inverter 100) including a DC bus bar (bus bar 32) for transmitting a direct current and an electronic component (capacitor 33, power module 30) connected to the DC bus bar. Has a first terminal (bus bar terminal 32a, 32b) for connecting to an electronic component, and the electronic component has a second terminal (capacitor terminal 34, power module terminal 31) for connecting to the first terminal. ), And the first terminal and the second terminal are the joint surfaces of the first terminal and the second terminal in either the first terminal or the second terminal. A fillet weld where the first terminal and the second terminal are melt-bonded at at least one end of the lap weld and the first terminal, which reach from the opposite surface to the other terminal and are welded. And have. By doing so, the terminal welded joint of the present invention can be adopted in the power conversion device.

In the embodiment described above, when the bus bar terminals 32a and 32b of the bus bar 32 are welded to the capacitor terminal 34 and the power module terminal 31, respectively, the fillet welded portion and the lap welded portion are on the bus bar terminal 32a and 32b side. Although the example of forming each of the above is described, the fillet welded portion and the lap welded portion may be formed on the capacitor terminal 34 and the power module terminal 31 side. Even in this way, the terminal welded joint of the present invention can be applied to the welding of the bus bar 32, the capacitor 33, and the power module 30 in the inverter 100.

Further, it is possible to delete, replace with another configuration, or add another configuration without departing from the technical idea of the invention, and the embodiment thereof is also included in the scope of the present invention.

1a, 1aA, 1b, 1bA ... Terminal 2, 2A ... Welded part 2a, 2aA ... Fillet welded part 3, 3A ... Laminated welded part 10 ... Laser 11 ... Shielded gas nozzle 12 ... Shield gas 13 ... Laser processing head 14 ... Laser oscillator 15 ... Optical fiber 16 ... XY stage 27 ... Slit 30 ... Power module 31 ... Power module terminal 32 ... ... Bus bar 32a, 32b ... Bus bar terminal 33 ... Capacitor 34 ... Capacitor terminal 100 ... Inverter

Claims (5)

A welded joint having a welded structure in which a first member and a second member, which are rectangular plates, are superposed on each other and joined to each other.
The welded portion that joins the first member and the second member is a lap weld portion that reaches from the surface of the first member opposite to the second member to the second member. A terminal welded joint having a fillet welded portion in which the first member and the second member are melt-bonded at at least one end of the first member. The terminal welded joint according to claim 1.
The fillet weld is a terminal welded joint formed on the edge of the opening of the first member. The terminal welded joint according to claim 1.
The first member and the second member are terminal welded joints containing copper or aluminum as a main component. The terminal welded joint according to claim 1.
A terminal welded joint in which the width of the lap weld is larger than the width of the fillet weld. A power conversion device including a DC bus bar that transmits a direct current and an electronic component connected to the DC bus bar.
The DC bus bar has a first terminal for connecting to the electronic component.
The electronic component has a second terminal for connecting to the first terminal.
The first terminal and the second terminal are arranged so as to be overlapped with each other.
The welded portion that joins the first terminal and the second terminal is a joint between the first terminal and the second terminal at either the first terminal or the second terminal. At least one end of a lap weld portion that reaches and is welded from a surface opposite to the surface to the other terminal and one of the first terminal and the second terminal, the first terminal. A power conversion device having a fillet welded portion in which the terminal of the above and the second terminal are melt-bonded.

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