Terminal unit and method of manufacturing the same

1. Field of the Invention

The present invention relates to a terminal unit and a method of manufacturing the terminal unit.

2. Description of Related Art

Conventionally, to press fit terminal parts of rod shape into holes formed on electrode parts such as current collection plates, or to crimp terminal parts after inserting the terminal parts into holes of electrode parts provides terminal units with fixing structure of the terminal parts to the electrode parts, and batteries equipped with the terminal units having the fixing structures are well known (e.g. see JP 2005-285406 A).

JP 2005-285406 A discloses a conventional terminal unit, in which the metal oxide films formed on each surface of the parts surrounds the contacting area of the terminal part to the electrode part. Unfortunately, the unevenness of the electrical conductivity occurs depending on the condition of press fitting or crimping. Therefore, the batteries including conventional terminal units mentioned above tend to vary in quality.

The present invention relates to a technique of a terminal unit having a press fitting structure of a terminal part into an electrode part and aims to provide a terminal unit capable of preventing a vary in electrical conductivity thereof by means of fixing the terminal part to the electrode part with removing the oxide films formed on the parts.

The first aspect of the present invention is a terminal unit which contains an electrode part disposed in a case, for connecting with an electrode body and a terminal part having a rod shape with a first end and a second end, the first end for fixing to the electrode part, and the second end extending outside of the case.

In one embodiment of the first aspect of the invention, the electrode part includes an insert hole into which the terminal part is inserted, the terminal part comprises an insert portion having an insert portion having a larger diameter than that of the hole and formed at the first end and a tip portion having a smaller diameter than that of the hole and formed at the nearer side of the first end than the insert portion. And, the clinch portion is press fitted into the insert hole, thereby fixing the terminal part to the electrode part.

Accordingly, when press fitting the terminal part into the electrode part, the insert portion having larger diameter than the insert hole pares off the oxide films formed on the electrode part.

Therefore, the electric conductivity between the terminal part and the electrode part is secured, thereby preventing varying in quality of the electric products with the terminal unit.

In the preferable embodiment of the terminal unit, the terminal part is made of harder substance than the electrode part.

Accordingly, the insert portion of the terminal part removes the oxide film on the electrode part.

In the advantageous embodiment of the terminal unit, the insert portion has an uneven surface having projections and recesses at a periphery thereof and the tip portion has a tapered portion being tapered from the first end toward the second end.

Accordingly, the uneven surface of the insert portion enlarges the contacting area between the terminal part and the electrode part, thereby enhancing the electric conductivity thereof. Furthermore, the neck portion of the tapered portion receives the materials pared off by the uneven surface in press fitting. As a result, the generation of the chips in press fitting is prevented.

The second aspect of the present invention is a method of manufacturing a terminal unit which contains an electrode part disposed in a case, for connecting with an electrode body and a terminal part having a rod shape with a first end and a second end, the first end for fixing to the electrode part, and the second end extending outside of the case.

In one embodiment of the second aspect of the invention, it includes a step of providing an insert hole for inserting the terminal part with the electrode part and of providing a clinch portion with the terminal part comprising an insert portion having a larger diameter than that of the hole and formed at the first end; and a tip portion having a smaller diameter than that of the hole and formed at the nearer side of the first end than the insert portion. It also includes a step of press fitting the clinch portion into the insert hole for fixing the terminal part to the electrode part.

Accordingly, when press fitting the terminal part into the electrode part, the insert portion having larger diameter than the insert hole pares off the oxide films formed on the electrode part.

Therefore, the electric conductivity between the terminal part and the electrode part is secured, thereby preventing varying in quality of the electric products with the terminal unit.

In the preferable embodiment of the manufacturing method, the terminal part is made of harder substance than the electrode part.

Accordingly, the insert portion of the terminal part removes the oxide film on the electrode part.

In the advantageous embodiment of the manufacturing method, it further includes a step of providing the insert portion with an uneven surface having projections and recesses at a periphery thereof and of providing the tip portion with a tapered portion being tapered from the first end toward the second end.

Accordingly, the uneven surface of the insert portion enlarges the contacting area between the terminal part and the electrode part, thereby enhancing the electric conductivity thereof. Furthermore, the neck portion of the tapered portion receives the materials pared off by the uneven surface in press fitting. As a result, the generation of the chips in press fitting is prevented.

According to the present invention, the varying of electric conductivity in the terminal unit is prevented.

FIG. 1 is a sectional view of a battery containing terminal units according to the present invention.

FIG. 2 is a schematic view of the terminal units assembled into the battery, (a) showing the negative side and (b) showing the positive side.

FIG. 3 is a schematic view of a terminal part.

FIG. 4 is a schematic view of an insert portion of the terminal part viewed from the arrow A in FIG. 3 , (a) showing a knurling configuration, (b) showing a tooth forming configuration and (c) showing a petaloid forming configuration.

FIG. 5 is a sectional view of an electrode part.

FIG. 6 is an enlarged sectional view showing a relationship between the terminal part and the electrode part in assembling.

FIG. 7 is an enlarged sectional view showing a manufacturing method of the terminal unit, showing before assembling.

FIG. 8 is an enlarged sectional view showing the manufacturing method of the terminal unit, showing after assembling.

Referring FIG. 1 , the whole structure of a battery 1 will be described, which includes terminal units 4 , 9 , each of which is one embodiment of a terminal unit according to the present invention.

It should be noted that the battery 1 including the terminal units 4 , 9 is described in this description, though the terminal unit according to the present invention may be broadly applied, not limited to the battery.

As shown in FIG. 1 , the battery 1 is a box-shaped lithium-ion battery, containing a case 2 , an electrode body 3 , and the terminal units 4 , 9 .

The case 2 is composed of a lid part 2 a and a case part 2 b , and is filled with an electrolyte solution 18 that behave as an electrically conductive medium.

The electrode body 3 is, for example, composed of a negative electrode sheet 3 a such as a copper sheet coated with a carbon substance, a positive electrode sheet 3 b such as a aluminum sheet coated with a lithium-ion compound and a separator sheet 3 c , and the sheets 3 a , 3 b are winded through the sheet 3 c , thereby forming the electrode body. The sheets 3 a , 3 b are connected to plural wires 14 , 15 , respectively, as electrical paths. The wires 14 , 15 are connected to the terminal units 4 , 9 , respectively.

The terminal unit 4 contains an electrode part 8 and a terminal part 5 , and serves as a negative terminal composed of copper (hereinafter, called a negative terminal unit). The terminal unit 9 contains an electrode part 13 and a terminal part 10 , and serves as a positive terminal composed of aluminum (hereinafter, called a positive terminal unit).

The electrode parts 8 , 13 are disposed in the case 2 and connected with the wires 14 , 15 . The terminal parts 5 , 10 have a rod shape and the one ends is fixed to the electrode parts 8 , 13 and the other ends extend outside of the case 2 .

That is, the first ends 5 a , 10 a of the terminal parts 5 , 10 are fixed to the electrode parts 8 , 13 , which integrates them, and thus the terminal units 4 , 9 are formed.

With reference to FIGS. 1 and 2 , the fixing structure of the terminal units 4 , 9 to the lid part 2 a will be described.

As shown in FIGS. 1 and 2 , the second ends 5 b , 10 b of the terminal parts 5 , 10 goes through the holes 2 c , 2 d formed at the lid part 2 a , thereby the second ends extending outside of the case 2 .

The negative terminal unit 4 is connected to the negative electrode sheet 3 a via the wires 14 , the positive terminal unit 9 is connected to the positive electrode sheet 3 b via the wires 15 . Thus, the terminal units 4 , 9 provide the electric paths among inside and outside of the case 2 .

The holes 2 c , 2 d are covered with seal parts 16 , 17 . In other words, the seal parts 16 , 17 are arranged between the terminal parts 5 , 10 and the holes 2 c , 2 d , and the terminal parts 5 , 10 are arranged, thereby insulating between the lid part 2 a and the terminal part 5 , 10 . At the same time, the seal parts 16 , 17 seal between the holes 2 c , 2 d and the terminal parts 5 , 10 and between the lid parts 2 a and the terminal parts 5 , 10 , thus, preventing leakage of the electrolyte solution 18 .

As shown in FIG. 2 , the seal parts 16 , 17 have outer parts 16 a , 17 a and inner parts 16 b , 17 b , thereby providing separate structures, which makes it easy to attach the seal parts 16 , 17 to the holes 2 c , 2 d.

Referring FIGS. 3 to 6 , the structures of the terminal units 4 . 9 will be followed.

Here, the structure of the positive terminal unit 9 is the same as that of the terminal unit 4 , so the structure of the negative terminal unit 4 is shown in FIGS. 3 to 6 , and the references of the positive terminal unit 9 are tagged to the corresponding members of the negative terminal unit 4 .

As mentioned above, the terminal units 4 , 9 contain the terminal parts 5 , 10 and electrode parts 8 , 13 , respectively.

As shown in FIG. 3 , the terminal part 5 of the negative terminal unit 4 is a cylindrical metal member and has a clinch portion 7 , at the first end 5 a , for fixing the terminal part 5 to the electrode part 8 .

The clinch portion 7 includes: an insert portion 7 b having a cylinder shape and formed with an uneven surface 7 a at the periphery of the insert portion; and a tip portion 7 d arranged at the nearer side of the first end than the insert portion 7 b and formed with a tapered portion 7 c that is tapered toward the insert portion 7 b (tapered from the first end 5 a toward the second end 5 b ).

The second end 5 b of the terminal part 5 has a connecting portion 6 used for constructing an assembled battery containing the batteries 1 or for connecting with the electrical devices disposed outside of the battery 1 . For example, the connecting portion 6 has a male thread and fitted to the bus bars via the nuts. So, the assembled battery is constructed by assembling the batteries 1 .

The terminal part 5 has a large diameter portion 5 c in the middle, which provides a stepped structure, thereby sealing between the terminal part 5 and the seal part 16 .

As shown in FIG. 3 , the terminal part 10 of the negative terminal unit 9 is a cylindrical metal member and has a clinch portion 12 , at the first end 10 a , for fixing the terminal part 10 to the electrode part 13 .

The clinch portion 12 includes: an insert portion 12 b having a cylinder shape and formed with an uneven surface 12 a at the periphery of the insert portion; and a tip portion 12 d arranged at the nearer side of the first end than the insert portion 12 b and formed with a tapered portion 12 c that is tapered toward the insert portion 12 b (tapered from the first end 10 a toward the second end 10 b ).

The second end 10 b of the terminal part 10 has a connecting portion 11 used for constructing an assembled battery containing the batteries 1 or for connecting with the electrical devices disposed outside of the battery 1 . For example, the connecting portion 11 has a male thread and fitted to the bus bars via the nuts. So, the assembled battery is constructed by assembling the batteries 1 .

The terminal part 10 has a large diameter portion 10 c in the middle, which provides a stepped structure, thereby sealing between the terminal part 10 and the seal part 17 .

In this embodiment, the terminal part 5 of the negative terminal unit 4 is made of copper-chromium alloys (CuCr), and the terminal part 10 of the positive terminal unit 9 is made of aluminum (A6061-T6).

In this case, the terminal units 4 , 9 are constructed by two parts (the terminal parts 5 , and the electrode parts 8 , 13 ). Thus, in comparison with the alternative embodiment of the terminal units which are constructed as a one-piece containing a terminal portion and electrode portion, the terminal units as this embodiment composed of two-piece have advantages in terms of facilities and costs for manufacturing.

The periphery of the insert portions 7 b , 12 b of the terminal parts 5 , 10 are rough surfaces such as projections and recesses. As shown in FIG. 4 , the portions 7 b , 12 b , viewed from arrow A represented in FIG. 3 , are configured in parallel knurl shape (shown in FIG. 4 ( a )), in tooth form (shown in FIG. 4 ( b )), or in petaloid shape (shown in FIG. 4 ( c )).

In these embodiments shown in FIG. 4 , the diameters D 3 of the tip portions 7 d , 12 d are smaller than the diameters D 2 of the insert portions 7 b , 12 b , and the diameters D 2 are smaller than the diameters D 1 of the terminal parts 5 , 10 .

As shown in FIG. 5 , the electrode part 8 of the negative terminal unit 4 is a metal member manufactured by bending a plate, and the electrode part has a fixing portion 8 a for fixing the terminal part 5 and an electrode portion 8 b for collecting the wires 14 and for connecting to the electrode body 3 . The fixing portion 8 a has an insert hole 8 c at the position where the terminal part 5 is fixed.

As shown in FIG. 5 , the electrode part 13 of the negative terminal unit 9 is a metal member manufactured by bending a plate, and the electrode part has a fixing portion 13 a for fixing the terminal part 10 and an electrode portion 13 b for collecting the wires 15 and for connecting to the electrode body 3 . The fixing portion 13 a has an insert hole 13 c at the position where the terminal part 10 is fixed.

In this embodiment, the electrode part 8 of the negative terminal unit 4 is made of pure copper (C1100), and the electrode part 13 of the positive terminal unit 9 is made of pure aluminum (A1050).

As shown in FIG. 6 , the diameters D 4 of the holes 8 c , 13 c are larger than the diameters D 3 of the tip portions 7 d , 12 d , so that the tip portions 7 d , 12 d are smoothly inserted into the holes 8 c , 13 c . The diameters D 4 are smaller than the diameters D 2 of the insert portions 7 b , 12 b.

The dimensions of the terminal parts 5 , 10 shown in FIG. 6 are followed: the diameters D 1 of the terminal parts 5 , 10 are about 6 mm; the heights H 1 are about 20 mm; the diameters D 2 of the insert portions 7 b , 12 b are about 5 mm; the heights H 2 are about 1 mm; the diameters D 3 of the tip portions 7 d , 12 d are about 4.5 mm; and the heights H 3 are about 0.5 mm. The dimensions of the electrode parts 8 , 13 are followed: the diameters D 4 of the holes 8 c , 13 c are about 4.6 mm; and the thickness H 4 of the fixing portions 8 a , 13 a are about 1.5 mm.

With respect to the uneven surfaces 7 a , 12 a of the clinch portions 7 , 12 formed in the terminal parts 5 , 10 , the uneven surfaces have parallel projections to the press fitting direction of the terminal parts 5 , 10 (in this embodiment, the axis direction of the terminal parts 5 , 10 of cylindrical shape), and when press fitting of the clinch portions 7 , 12 into the insert holes 8 c , 13 c , the projections pare off the inner surface of the holes 8 c , 13 c . If these actions are satisfied, the configuration of the uneven surfaces 7 a , 12 a are not limited to the embodiments shown in FIG. 4 .

Referring FIGS. 7 , 8 , the manufacturing method of the terminal units 4 , 9 will be described.

Here, the manufacturing method (assembling procedure) of the positive terminal unit 9 is the same as that of the terminal unit 4 , so the assembling procedure of the negative terminal unit 4 is shown in FIGS. 7 , 8 , and the references of the positive terminal unit 9 are tagged to the corresponding members of the negative terminal unit 4 .

As shown in FIG. 7 , when assembling the negative terminal unit 4 , the tip portion 7 d is inserted into the insert hole 8 c , thereby positioning the terminal part 5 with regard to the electrode part 8 .

As shown in FIG. 8 , the lower face of the fixing portion 8 a is pressed by a lower die 20 a of the press apparatus, and the second end 5 b of the terminal part 5 is pressed downwardly by an upper die (punch) 20 b of the press apparatus, then the clinch portion 7 (insert portion 7 b ) is press fitted into the insert hole 8 c . Thus, the terminal part 5 and the electrode part 8 are integrated, whereby manufacturing the negative terminal unit 4 . In this case, the pressure of the press apparatus is about 20 MPa.

When assembling the positive terminal unit 9 , the tip portion 12 d is inserted into the insert hole 13 c , thereby positioning the terminal part 10 with regard to the electrode part 13 .

The lower face of the fixing portion 13 a is pressed by the lower die 20 a of the press apparatus, and the second end 10 b of the terminal part 10 is pressed downwardly by the upper die (punch) 20 b of the press apparatus, then the clinch portion 12 (insert portion 12 b ) is press fitted into the insert hole 13 c . Thus, the terminal part 10 and the electrode part 13 are integrated, whereby manufacturing the positive terminal unit 9 .

The relationship of hardness between the terminal part 5 and the electrode part 8 is followed: the Vickers hardness of the copper-chromium alloys (CuCr) is about 140 HV; that of the pure copper (C1100) is about 80 HV, thus, the terminal part 5 is made of harder substance than the electrode part 8 . Accordingly, when press fitting the clinch portion 7 into the insert hole 8 c , the insert portion 7 b (in detail, the projections formed on the uneven surface 7 a of the insert portion 7 b ) pares off the inner surface of the insert hole 8 c.

At the same time of paring off the inner surface of the insert hole 8 c , the oxide film is removed from the inner surface of the insert hole 8 c , thereby securing the electrical conductivity between the terminal part 5 and the electrode part 8 .

Due to the uneven surface 7 a , the surface area of the insert portion 7 b becomes larger than the case without the uneven surface 7 a . Thus, the contact area between the insert hole 8 c and the insert portion 7 b becomes larger, thereby enhancing the electrical conductivity between the terminal part 5 and the electrode part 8 .

Further, the neck portion formed at the tip portion 7 d (the small diameter portion of the tapered portion 7 c ) receives the materials (pure copper) pared off around the insert hole 8 c.

If the materials pared off at press fitting drop into the case 2 , they will cause a short circuit of the battery 1 and thus lower the quality thereof. However, due to the configuration of the negative terminal unit 4 , the pared off materials (pure copper) will be received into the neck portion of the tapered portion 7 c , and they will be forced into the space between the small diameter portion of the tapered potion 7 c and the insert hole 8 c . Accordingly, the fixing force is heightened between the terminal part 5 and the electrode part 8 .

As mentioned above, the chips generated in press fitting are enclosed in the clinch portion 7 , preventing drop into the case 2 . That is to say, regarding the negative terminal unit 4 configured like that, the chips would not disperse from the insert hole 8 c when assembling, so that the terminal unit with the configuration is suitable not only for the battery 1 but also for other battery (e.g. a fuel battery) and electrical components such as a capacitor.

It should be noticed that the copper-chromium alloys (CuCr) and the pure copper (C1100) are employed as the substances of the terminal part 5 and the electrode part 8 , respectively, of the negative terminal unit 4 , which does not limit the substances employed for the negative terminal unit according to the present invention, and the various combination may be employed where the terminal part is harder than the electrode part.

With respect to the positive terminal unit 9 , the relationship of hardness between the terminal part 10 and the electrode part 13 , which is as the same as that of the negative terminal unit 4 , is followed: the Vickers hardness of the aluminum (A6061-T6) is about 105 HV; that of the pure aluminum (A1050) is about 30 HV, thus, the terminal part 10 is made of harder substance than the electrode part 13 .

As described before, the configuration of the positive terminal unit 9 provides the same action as the negative terminal unit 4 .

It should be noticed that the aluminum (A6061-T6) and the pure aluminum (A1050) are employed as the substances of the terminal part 10 and the electrode part 13 , respectively, of the positive terminal unit 9 , which does not limit the substances employed for the positive terminal unit according to the present invention, and the various combination may be employed where the terminal part is harder than the electrode part.