Heterogeneous metal bus bar and manufacturing method thereof

Abstract

To provide a heterogeneous metal bus bar improved in strength, conductivity and cost.SOLUTION: A heterogeneous metal bus bar 1 consists of a first metal body 10, which is connected to a cathode terminal of a battery and is the same metal as the cathode terminal, and a second metal body 20 which is connected to an anode terminal of the other battery and is the same metal as the anode terminal. In the heterogeneous metal bus bar, the first metal body includes one or more through holes 11, and the second metal body is press-fitted into the through holes of the first metal body. The heterogeneous metal bus bar has a simple structure in which the second metal body is inserted into the through holes of the first metal body, but is improved in adhesiveness and conductivity. Further, since the second metal body of high material cost is used partially, cost of manufacture is kept low.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a dissimilar metal bus bar used when assembling a secondary battery in which a positive electrode terminal and a negative electrode terminal are formed of different metals into a battery pack, and a method for manufacturing the same.

Background Art

[0002] As a secondary battery mounted on an electric vehicle or the like, it is known to configure a battery pack by connecting a plurality of battery cells to each other with a bus bar so that the positive and negative electrodes are connected in series. As a typical battery cell, a lithium-ion secondary battery is used. Most of the lithium-ion secondary batteries have a positive electrode terminal formed of aluminum (Al) as a material and a negative electrode terminal formed of copper (Cu) as a material.

[0003] There is a bus bar as a component for connecting such terminals of battery cells. When connecting battery cells in series, an aluminum terminal that is a positive electrode terminal and a copper terminal that is a negative electrode terminal are connected by a bus bar. Therefore, whether the bus bar is formed of aluminum or copper, there must be a connection between the bus bar and one of the terminals by different metals. Generally, when different metals are connected, electrolytic corrosion due to moisture in the air occurs. As the electrolytic corrosion progresses, the connection between the bus bar and the terminal may become non-conductive, or the bus bar itself or the terminal itself may be damaged, and ultimately, there may be a serious problem such as the inability to start an electric vehicle.

[0004] Therefore, as something created in view of the above problems, a dissimilar metal bus bar shown in Patent Document 1 is known. This dissimilar metal bus bar has a positive electrode connection portion formed of the same metal as the positive electrode terminal of the battery cell and connectable to the positive electrode terminal, and a negative electrode connection portion formed of the same metal as the negative electrode terminal of the battery cell and connectable to the negative electrode terminal, which are integrally joined by extrusion processing.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2011 - 210480 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, in a method of joining end faces of plate - shaped dissimilar metals by extrusion processing like a conventional dissimilar - metal bus bar, the strength and conductivity were insufficient.

[0007] The present invention was created in view of the above problems, and an object thereof is to provide a dissimilar - metal bus bar excellent in strength, conductivity, and cost. [Means for Solving the Problems]

[0008] The above problems can be solved by a dissimilar - metal bus bar that is connected to the positive - electrode terminal of a battery and is composed of a first metal body made of the same metal as this, and a second metal body made of the same metal as this and connected to the negative - electrode terminal of another battery, wherein the first metal body has one or more through - holes, and the second metal body is press - fitted into the through - holes of the first metal body.

[0009] It is preferable that retaining means are formed at both ends of the second metal body.

[0010] It is preferable that a knurled portion is formed on the outer peripheral surface of the second metal body as an anti - rotation means.

[0011] Alternatively, the above problem can be solved by a method for manufacturing a dissimilar metal bus bar composed of a first metal body connected to the positive electrode terminal of a battery and made of the same metal as this, and a second metal body connected to the negative electrode terminal of another battery and made of the same metal as this. The first metal body has one or more through holes, a cylindrical second metal body is press-fitted into the through holes of the first metal body, and a punch pin is further inserted into the second metal body to expand the second metal body, thereby bringing it into close contact with the first metal body.

[0012] In addition, it is desirable to form a retaining means by expanding the end portion of the second metal body during the process of pulling out the punch pin.

[0013] In addition, the second metal body preferably has a knurled portion on its outer peripheral surface, and the second metal body is press-fitted into the through hole of the first metal body.

Advantages of the Invention

[0014] According to the present invention, since the second metal body is press-fitted into the through hole of the first metal body, a dissimilar metal bus bar excellent in adhesion and conductivity can be provided. Further, since the second metal body, which has a high material cost, is partially used, a dissimilar metal bus bar with a low manufacturing cost can be provided.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the dissimilar metal bus bar and its manufacturing method according to the present invention will be described with reference to the drawings.

[0017] In FIG. 1, reference numeral 1 denotes a dissimilar metal bus bar for electrically connecting a plurality of batteries to form a battery pack. This dissimilar metal bus bar 1 is connected to the positive electrode terminal of a battery and is composed of a first metal body 10 made of the same metal as this, and a second metal body 20 made of the same metal as this and connected to the negative electrode terminal of another battery. For example, the first metal body 10 is made of an aluminum material, and the second metal body 20 is made of a copper material.

[0018] The first metal body 10 is a plate having one or more through holes 11.

[0019] The second metal body 20 is a collar in which a flange portion 23 is integrally formed on the outer periphery of an end portion of a main body 21 having a sleeve hole 22. Note that a knurl or a longitudinal groove may be formed in all or part of the outer peripheral surface of the main body 21 of the second metal body 20.

[0020] As a manufacturing method of the dissimilar metal bus bar 1, a receiving die 2 is formed in a sleeve shape that can communicate with the through hole 11 of the first metal body 10. Therefore, as a first step, as shown in FIG. 2, the first metal body 10 is placed on the upper surface of the receiving die 2, and the main body 21 of the second metal body 20 is inserted into the through hole 11 of the first metal body 10. At this time, the fitting tolerance between the inner diameter of the through hole 11 of the first metal body 10 and the outer diameter of the main body 21 of the second metal body 20 can be appropriately selected from clearance fit, interference fit, transition fit, etc.

[0021] Subsequently, as a second step, as shown in FIG. 3, a knockout pin 3 is inserted into the sleeve hole 22 of the second metal body 20. At this time, since the outer diameter of the knockout pin 3 is set to be larger than the inner diameter of the sleeve hole 22 of the second metal body 20, the main body 21 of the second metal body 20 will be pushed and expanded outward. For this reason, the main body 21 of the second metal body 20 is fixed in close contact with the inner peripheral surface of the through hole 11 of the first metal body 10. Note that the cross-sectional shape of the knockout pin 3 is not limited to a perfect circle, and may be an ellipse or a polygon.

[0022] Finally, as a third step, as shown in FIG. 4, the knockout pin 3 is pulled out from the sleeve hole 22 of the second metal body 20. At this time, since the tip of the knockout pin 3 has a return portion 3a formed with a diameter larger than that of the main body, the end portion 24 of the main body 21 of the second metal body 20 is caught by the return portion 3a of the knockout pin 3 and expands, thereby forming a retaining means.

[0023] According to the method for manufacturing the dissimilar metal bus bar 1, since the dissimilar metal bus bar is mechanically manufactured instead of by welding such as pressure welding or laser welding, the manufacturing cost is excellent. Further, the dissimilar metal bus bar 1 manufactured by this manufacturing method is excellent in the adhesion and conductivity between the first metal body 10 and the second metal body 20, and thus sufficiently satisfies the performance required for the bus bar. Further, the dissimilar metal bus bar 1 is provided with a second metal body 20 made of a copper material on a part of the first metal body 10 made of an aluminum material, that is, the second metal body 20 is provided only in a necessary portion, so that the material cost can be kept low.

[0024] Further, since the second metal body 20 is provided with retaining means at both ends by the flange portion 23 and the end portion 24 where the retaining means is formed, the second metal body 20 is configured not to fall off from the first metal body 10.

[0025] Note that the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, in the first to third steps, it is preferable that the first metal body 10 and the second metal body 20 are pressed by a mold from above so that these metal bodies 10 and 20 do not warp.

[0026] 1 Dissimilar metal bus bar 2 Receiving mold 3 Knockout pin 3a Return portion 10 First metal body 11 Through hole 20 Second metal body 21 Main body 22 Sleeve hole 23 end 24 flange

Claims

1. In a dissimilar metal bus bar composed of a first metal body connected to the positive electrode terminal of a battery and made of the same metal as this, and a second metal body connected to the negative electrode terminal of another battery and made of the same metal as this, the dissimilar metal bus bar, wherein the first metal body has one or more through holes, and the second metal body is press-fitted into the through holes of the first metal body.

2. The dissimilar metal bus bar according to claim 1, wherein anti-slip is formed at both ends of the second metal body.

3. The dissimilar metal bus bar according to claim 1 or 2, wherein a knurled portion is formed on the outer peripheral surface of the second metal body as an anti-rotation measure.

4. In a method for manufacturing a dissimilar metal bus bar composed of a first metal body connected to the positive electrode terminal of a battery and made of the same metal as this, and a second metal body connected to the negative electrode terminal of another battery and made of the same metal as this, the method for manufacturing a dissimilar metal bus bar, wherein the first metal body has one or more through holes, a cylindrical second metal body is press-fitted into the through holes of the first metal body, and a punch pin is inserted into the second metal body to expand the second metal body so as to be in close contact with the first metal body.

5. The method for manufacturing a dissimilar metal bus bar according to claim 4, wherein anti-slip is formed by expanding the end portion of the second metal body in the process of pulling out the punch pin.

6. The method for manufacturing a dissimilar metal bus bar according to claim 4 or 5, wherein the second metal body has a knurled portion on its outer peripheral surface, and the second metal body is press-fitted into the through holes of the first metal body.

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