Method for welding busbars and busbar structure

Abstract

The present application is a welding method for a busbar (6) having the following steps: preparing the busbar (6) having a first flat portion (2), a curved portion (5), and a second flat portion (1) in this order in the longitudinal direction; bringing the joint surface (4) of the joined body (3) into contact with the first flat portion (2) of the busbar (6); and performing butt welding by irradiating laser light to a groove portion (7) formed by the joint surface (4) of the joined body (3) and the curved portion (5) of the busbar (6), thereby joining the busbar (6) to the joined body (3).

Description

Technical Field

[0001] This invention relates to a welding method for busbars. Background Technology

[0002] For example, in electric vehicles that use a motor as a driving force, power is supplied to the motor from an inverter. Therefore, an electrical connection box, terminal block, or other electrical connection body is provided to electrically connect the motor and the inverter. A busbar is provided on such an electrical connection body, and wiring harnesses or other power distribution components are connected to both ends of the busbar to form the circuit of the electric vehicle or the like.

[0003] In the past, various studies have been conducted to effectively join busbars. Patent Document 1 (Japanese Patent Application Publication No. 10-334957) discloses a laser welding structure for a busbar, in which protrusions standing out from the patterned portions of different layers of a stacked busbar overlap each other, and a laser beam is used to weld the overlapping protrusions together. Patent Document 2 (Japanese Patent Application Publication No. 11-297380) discloses a busbar structure for an electrical connection box, in which a short terminal holding portion is formed on the busbar, and on the other hand, only a contact portion for inserting terminals of electronic components is provided on the upper relay terminal. A press-in portion is integrally formed on the relay terminal to press into the terminal holding portion of the busbar, and the press-in portion is pressed into the terminal holding portion of the busbar for joining.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 10-334957

[0007] Patent Document 2: Japanese Patent Application Publication No. 11-297380 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In the laser welding structure of Patent Document 1, when overlapping the tab-shaped portions of the stacked busbars, the tab-shaped portions need to overlap with precise positional accuracy. Therefore, if the upper surfaces of one tab-shaped portion and the upper surfaces of another tab-shaped portion are misaligned when overlapping the tab-shaped portions, it is difficult to achieve sufficient welding joint between the overlapping tab-shaped portions. Furthermore, in the laser welding structure of the busbars in Patent Document 1, when a force is applied to the stacked busbars in a direction of separation, gaps are created in the overlapping portions, and laser or electron beams pass through these gaps, making welding with laser or electron beams difficult.

[0010] In the busbar structure of the electrical connection box in Patent Document 2, since the busbar is welded to the socket terminal (relay terminal), space is required for the socket terminal, making miniaturization of the electrical connection box difficult. In addition, the increase in electrical connection points between the busbar and the socket terminal leads to problems such as heat generation and reduced reliability.

[0011] The present invention was made in view of the above-mentioned problems, and its object is to provide a welding method for welding a busbar to a workpiece in a way that enables efficient welding of the busbar to the workpiece.

[0012] Methods for solving problems

[0013] The welding method of the busbar of the present invention includes the following steps: preparing a busbar having a first flat portion, a curved portion and a second flat portion in sequence along its long side; contacting the joint surface of the workpiece with the first flat portion of the busbar; and performing butt welding by irradiating a groove formed by the joint surface of the workpiece and the curved portion of the busbar with a laser, thereby joining the busbar with the workpiece.

[0014] According to the welding method of the busbar of the present invention, butt welding is performed by irradiating a groove formed by the joint surface of the joined bodies and the curved portion of the busbar with a laser, thereby enabling bevel welding. Therefore, compared with the case of welding the portion where the tabs of the busbar overlap, as in Patent Document 1, stable weld quality and weld area can be obtained. In addition, since the contact area between the joint surface of the joined bodies and the first planar portion is large, when butt welding is performed by irradiating the groove with a laser, damage to surrounding components caused by the laser passing through the joined bodies and the busbar, and material scattering of the joined bodies and the busbar can be suppressed. As a result, the busbar can be effectively welded to the joined bodies.

[0015] Additionally, "long side direction" refers to the direction perpendicular to the thickness and width directions of the busbar.

[0016] Alternatively, in the process of bringing the mating surface of the bonded body into contact with the first flat portion of the busbar, the mating surface of the bonded body can be brought into contact with the first flat portion of the busbar by pressing the second flat portion toward the long side of the second flat portion.

[0017] According to this structure, the force applied by pressing the second flat portion is easily and effectively transmitted to the portion where the mating surface of the joined body contacts the first flat portion through the deformation of the curved portion of the busbar. As a result, by making the mating surface of the joined body and the first flat portion fully parallel, the mating surface of the joined body can effectively contact the first flat portion.

[0018] Alternatively, in the process of preparing the busbar, a busbar in which the angle between the long side of the first planar portion and the long side of the second planar portion is greater than 90° and less than 110° is prepared.

[0019] According to this structure, the angle between the long side direction of the first flat portion and the long side direction of the second flat portion is greater than 90° and less than 110°, forming an obtuse angle slightly larger than 90°. Therefore, during the process of bringing the mating surface of the joined body into contact with the first flat portion of the busbar, the force applied to the second flat portion can be more effectively transmitted to the portion where the mating surface of the joined body contacts the first flat portion through the deformation of the bending portion of the busbar. Furthermore, typically, after the bending portion of the busbar deforms, the angle between the long side direction of the first flat portion of the busbar and the long side direction of the second flat portion of the busbar is approximately 90°. As a result, the mating surface of the joined body and the first flat portion can be fixed in a gapless abutment state, enabling reliable welding without the penetration of lasers or electron beams.

[0020] Alternatively, the joined body may be a terminal portion of a vehicle component.

[0021] Although multiple components are used in a car for multiple electrical connections, this structure allows for an excellent electrical connection between the car component and the busbar because the joined object is a car component. Furthermore, since there is no need to provide socket terminals for the busbar's electrical connection, the electrical connector including the busbar can be miniaturized, allowing for efficient use of space within the car for other components. Additionally, when the joined object is a car component, the mating surface can be a surface of a terminal portion protruding from the component. Moreover, the term "carbar" is not particularly limited; examples include cars powered by internal combustion engines and electric vehicles.

[0022] Alternatively, the components of the vehicle can be selected from relays, resistors, fuses, and current sensors.

[0023] According to this structure, the mating surfaces of components selected from relays, resistors, fuses, and current sensors, which are the joined parts, are welded to the busbar, thereby enabling an excellent electrical connection between the joined parts and the busbar.

[0024] The busbar structure of the present invention comprises: a busbar having a planar portion and a curved portion; a bonded body having a plate-like portion; and a groove formed from the plate-like portion to the curved portion by the planar portion of the busbar abutting against the plate-like portion of the bonded body.

[0025] According to this busbar structure, butt welding can be performed by irradiating the groove with a laser, thereby enabling bevel welding. Therefore, compared to the case in Patent Document 1, where the overlapping portions of the busbar's tabs are welded together, stable weld quality and weld area can be obtained. Furthermore, the large contact area between the plate-like portion of the joined body and the planar portion of the busbar prevents damage to surrounding components and material scattering from the joined body and busbar during butt welding by irradiating the groove with a laser. As a result, the busbar can be effectively welded to the joined body.

[0026] Invention Effects

[0027] A welding method is provided that enables the busbar to be effectively welded to the joint. Attached Figure Description

[0028] Figure 1 This is a diagram illustrating a welding method for a busbar in one embodiment. Detailed Implementation

[0029] Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This diagram illustrates the welding method of the busbar according to this embodiment. More specifically, Figure 1 (a) is a perspective view showing the process of contacting the mating surface of the workpiece with the first flat portion of the busbar, and the process of joining the busbar and the workpiece by butt welding by irradiating the groove with a laser. Figure 1 (b) is Figure 1 (a) is a cross-sectional view along the A-A' direction.

[0030] Figure 1 This indicates the portion where busbar 6 is joined to the connected body 3. The actual busbar extends towards the upper right of the attached figure. Figure 1 The busbar 6 represents the end portion of the busbar that is joined to the coupled body 3. Furthermore, the coupled body 3 is the terminal portion of a component mounted on a vehicle. Figure 1 The main body of the component is connected to the joined body 3.

[0031] Figure 1 This refers to a busbar structure. The busbar structure includes: a busbar 6 having a planar portion (first planar portion 2) and a curved portion 5; a bonded body 3 having a plate-shaped portion (the bonding surface 4 indicates the plane where the plate-shaped portion abuts against the first planar portion 2); and a groove 7 formed from the plate-shaped portion to the curved portion 5 through the contact between the planar portion (first planar portion 2) of the busbar 6 and the plate-shaped portion of the bonded body 3.

[0032] In the welding method of the busbar in this embodiment, firstly, a busbar 6 is prepared having a first flat portion 2, a curved portion 5, and a second flat portion 1 sequentially along its long side direction D5. For example... Figure 1 As shown in (a) and (b), the long side direction D5 represents a direction perpendicular to the thickness direction D6 and the width direction D7 of the busbar 6 at a specific location in the long side direction D5. Figure 1 As shown, the busbar 6 is integrally formed from a first planar portion 2, a curved portion 5, and a second planar portion 1. The first planar portion 2 is a plate-shaped portion having two opposing surfaces, and the second planar portion 1 is a plate-shaped portion having two opposing surfaces. The curved portion 5 has a shape bent at a predetermined curvature, with one side of the long side direction D5 of the curved portion 5 connected to the first planar portion 2, and the other side of the long side direction D5 of the curved portion 5 connected to the second planar portion 1. The first planar portion 2, the curved portion 5, and the second planar portion 1 are continuously arranged along the long side direction D5, thereby forming the end portion of the busbar 6. At this time, the long side direction D4 of the first planar portion 2 and the long side direction D3 of the second planar portion 1 are parallel to the long side direction D5.

[0033] In the prepared busbar 6, the angle formed by the long side direction D4 of the first flat portion 2 and the long side direction D3 of the second flat portion 1 can be set to a range greater than 90° and less than 110°. By setting the aforementioned angle to a range greater than 90° and less than 110°, and setting it to an obtuse angle slightly larger than 90°, during the process of bringing the mating surface 4 of the joined body 3 into contact with the first flat portion 2 of the busbar 6, the force applied to the second flat portion 1 along the D2 direction can be more effectively transmitted to the portion where the mating surface 4 of the joined body 3 contacts the first flat portion 2 through the deformation of the bending portion 5 of the busbar 6. Furthermore, as... Figure 1 As shown in (b), typically, after the bending portion 5 of the busbar 6 deforms, the angle between the long side direction D4 of the first planar portion 2 of the busbar 6 and the long side direction D3 of the second planar portion 1 of the busbar 6 is approximately 90°. As a result, the mating surface 4 of the bonded body 3 and the first planar portion 2 can be fixed in a gapless abutment state, enabling reliable welding even when lasers or electron beams cannot pass through. Furthermore, as... Figure 1As shown in (b), "the angle between the long side direction of the first planar portion and the long side direction of the second planar portion of the busbar" represents the angle at the intersection of the long side direction D4 of the first planar portion and the long side direction D3 of the second planar portion. "The angle between the long side direction of the first planar portion and the long side direction of the second planar portion" can be varied by deformation of the bending portion 5. For example, the "angle between the long side direction of the first planar portion and the long side direction of the second planar portion" in the process of bringing the mating surface of the joined body into contact with the first planar portion of the busbar is smaller than the "angle between the long side direction of the first planar portion and the long side direction of the second planar portion" in the busbar prepared in the process of preparing the busbar. Typically, the "angle between the long side direction of the first planar portion and the long side direction of the second planar portion" after welding is 90°.

[0034] Next, the mating surface 4 of the joined body 3 is brought into contact with the first flat portion 2 of the busbar 6.

[0035] More specifically, such as Figure 1 As shown in (a) and (b), by pressing the second flat portion 1 towards the jointed body side in the direction D2 of the long side D3 of the second flat portion 1, the joint surface 4 of the jointed body 3 comes into contact with the first flat portion 2 of the busbar 6. At this time, the force applied by pressing the second flat portion 1 is easily and effectively transmitted to the part of the joint surface 4 of the jointed body 3 that contacts the first flat portion 2 due to the deformation of the bending portion 5 of the busbar 6. As a result, the joint surface 4 of the jointed body 3 and the first flat portion 2 are made to be in a sufficiently parallel positional relationship, and the joint surface 4 of the jointed body 3 can effectively contact the first flat portion 2. The jointed body 3 is, for example, a terminal portion of a car component, which is selected from relays, resistors, fuses, and current sensors. When the jointed body 3 is a car component, the joint surface 4 can be set as a terminal portion protruding from the car component. In the busbar 6 before contacting the mating surface 4 of the joined body 3, if the angle between the long side direction D4 of the first flat portion 2 and the long side direction D3 of the second flat portion 1 is greater than 90°, the bending portion 5 is deformed by the force applied by pressing the second flat portion 1. Therefore, after contacting the mating surface 4, the angle between the long side direction D4 of the first flat portion 2 and the long side direction D3 of the second flat portion 1 of the busbar 6 is smaller than the angle between the long side direction D4 of the first flat portion 2 and the long side direction D3 of the second flat portion 1 of the busbar 6 before contacting the mating surface 4. Typically, as... Figure 1 As shown in (b), the angle between the long side direction D4 of the first planar portion 2 after contacting the mating surface 4 and the long side direction D3 of the second planar portion 1 is 90°. Furthermore, as... Figure 1As shown in (b), the joint surface 4 of the joined body 3 contacts the first flat portion 2 of the busbar 6, forming a groove 7 composed of the bent portion 5 and the joined body 3. The groove 7 serves as the bevel for butt welding as described later.

[0036] Next, as Figure 1 As shown in (a), a laser is irradiated from the direction D4 into the groove 7 formed by the mating surface 4 of the bonded body 3 and the curved portion 5 of the busbar 6, causing the laser to scan in the direction D1 for butt welding. This melts the materials constituting the bonded body 3 and the curved portion 5, thereby joining the busbar 6 to the bonded body 3. Alternatively, the bonded body 3 and the busbar 6 can also be plated. Regarding plating, since the laser has low reflectivity and is easily absorbed, the bonded body 3 and the curved portion 5 can be melted with less laser output.

[0037] According to this embodiment, the bending portion 5 is easily deformable due to its bending, and even if there are dimensional errors between the joined body 3 and the first flat portion 2, the deformation of the bending portion 5 can ensure good contact between the first flat portion 2 and the joined body 3. As a result, the first flat portion 2 of the busbar 6 can be brought into contact with the joint surface 4 without creating a gap between the first flat portion 2 and the joint surface 4 of the joined body 3. That is, when the first flat portion 2 is brought into contact with the joint surface 4 of the joined body 3, even if the joint surface 4 and the first flat portion 2 are not parallel, the deformation of the bending portion 5 can correct the positional relationship between the joint surface 4 of the joined body 3 and the first flat portion 2, ultimately bringing the joint surface 4 into contact with the first flat portion 2 in a manner where the joint surface 4 is parallel to the first flat portion 2.

[0038] According to this embodiment, laser irradiation is applied to the groove 7, which is formed by the mating surface 4 of the joined body 3 and the curved portion 5 of the busbar 6, to perform butt welding. Therefore, compared to the case in Patent Document 1 where the overlapping portions of the busbar's tabs are welded, stable welding quality and welding area can be obtained between the mating surface 4 of the joined body 3 and the first flat portion 2. Furthermore, because the contact area between the mating surface 4 of the joined body 3 and the first flat portion 2 is large, when butt welding is performed by irradiating the groove 7 with laser, damage to surrounding components caused by the laser passing through the joined body 3 and the busbar 6, and material scattering from the joined body 3 and the busbar 6, can be suppressed. Moreover, when the second flat portion 1 of the busbar 6 is electrically connected to components, power sources, etc., an external force is applied to the second flat portion 1 towards the joined body side in the long side direction D3, thus pressing the first flat portion 2 against the mating surface 4 of the joined body 3, making it difficult for the first flat portion 2 to separate from the mating surface 4 of the joined body 3. In addition, the elimination of socket terminals allows for the miniaturization of the electrical connector including the busbar 6.

[0039] In the above embodiments, the positional relationship between the terminal portion of the component and the main body of the component is not specified, but it is preferable that the main body of the component is not positioned in the direction in which the long side direction D5 extends towards the first flat portion 2. By arranging the terminal portion 3 and the main body of the component in this way, even if a gap is generated between the joint surface 4 of the terminal portion 3 and the first flat portion 2 of the busbar 6 and the laser passes through the gap between the terminal portion 3 and the busbar 6, the main body of the component will not be damaged. In addition, it is possible to suppress the scattering of sputtering material towards the main body during laser irradiation.

[0040] Label Explanation

[0041] 1: Second planar portion; 2: First planar portion; 3: Body to be joined; 4: Joint surface; 5: Bending portion; 6: Busbar; 7: Groove.

Claims

1. A method for welding a busbar, comprising the following steps: A busbar is prepared that has a first planar portion, a curved portion, and a second planar portion sequentially along its long side. Make the mating surface of the joined body contact the first planar portion of the busbar; and The busbar is joined to the workpiece by butt welding, which is performed by irradiating the groove formed by the joint surface of the workpiece and the curved portion of the busbar with a laser.

2. The welding method for the busbar according to claim 1, wherein, In the process of bringing the mating surface of the joined body into contact with the first planar portion of the busbar, By pressing the second flat portion toward the side of the object to be joined in the direction of the long side of the second flat portion, the joining surface of the object to be joined comes into contact with the first flat portion of the busbar.

3. The welding method for the busbar according to claim 2, wherein, In the process of preparing the busbar, Prepare a busbar in a range where the angle between the long side of the first plane and the long side of the second plane is greater than 90° and less than 110°.

4. The welding method for the busbar according to claim 1 or 2, wherein, The joined body is the terminal portion of a component of an automobile.

5. The welding method for the busbar according to claim 4, wherein, The components of the vehicle are selected from relays, resistors, fuses, and current sensors.

6. A busbar structure having: A busbar having a flat portion and a curved portion; The joined body, having a plate-like portion; and The groove is formed from the plate-shaped portion to the curved portion by abutting the flat portion of the busbar against the plate-shaped portion of the joined body.

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