JP2674904B2 - Electric double layer capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor, and more particularly to an exterior structure for an electric double layer capacitor.

[0002]

2. Description of the Related Art The structure of a conventional electric double layer capacitor is shown in FIG. In the same figure, (a) is a side view and (b) is a DD line sectional view thereof. This electric double layer capacitor is composed of an electric double layer capacitor element (hereinafter referred to as an element) 1 having a charge holding function, and a pair of leaded electrode plates 20a and 20b arranged on both sides thereof. The element 1 is formed by stacking a plurality of basic cells 2 as shown in the sectional structure of FIG. In this basic cell 2, a cylindrical insulating rubber 3 is divided into upper and lower parts by a porous separator 4, and the insulating rubber 3
The space inside is filled with an activated carbon paste electrode 5 made by kneading powdered activated carbon and dilute sulfuric acid, and the upper and lower sides thereof are sealed with a conductive plastic film 6. The porous separator 4 is ion-permeable and non-electroconductive. The withstand voltage of the basic cell 2 thus obtained is determined by the electrolysis voltage of dilute sulfuric acid and is as low as about 1.2 V. Therefore, the required number of layers is laminated according to the operating voltage to form the element 1.

In the element of such an electric double layer capacitor, there is an internal resistance such as a contact resistance between the activated carbon particles inside the basic cell 2 and a contact resistance between the basic cells 2 caused by adopting the laminated structure. To do. The magnitude of this internal resistance has a characteristic that it decreases as the pressure applied from above and below the element 1 increases, as shown in an example in FIG. 5, so in order to keep the internal resistance of the electric double layer capacitor as a whole small and maintain it. Needs to apply a considerable pressure to the element 1. The magnitude of this pressure is determined in consideration of the magnitude of internal resistance and pressure resistance of the element, but normally it is several tens of kg / cm ²
It is about.

Therefore, in order to maintain the pressure condition necessary for the element 1 and to operate as a capacitor, as shown in FIG.
20b are arranged, these are put in a molding die, and the element 1 is applied from the outside of each electrode plate 20a, 20b by a pressing pin.
The mold resin 7 is molded by molding under pressure. In addition, pressure pin hole 8
Is a hole formed for removing the pressure pin after the resin 7 hardens.

Here, the leaded electrode plates 20a, 20
An embossment 21 having a diameter smaller than the outer diameter of the element 1 is applied to b. This is because in the element 1 described above, the activated carbon paste electrode 5 filled in the central portion of the element 1 has a hardness close to that of a rigid body, and therefore the leaded electrode plates 20a, 20b.
When pressing the element 1 from both sides with, activated carbon paste electrode 5
Since the pressure is supported by the part, the insulating rubber 3 around
It becomes difficult to apply sufficient pressure to the. As a result, when the insulating rubber 3 and the conductive plastic film 6 are not sufficiently adhered to each other, or when the insulating rubber 3 has fine defects or weak portions, the activated carbon can be easily subjected to various life tests. There is a possibility that reliability may be deteriorated due to a so-called dry-up phenomenon in which moisture of the paste electrode 5 escapes and the function of the electric double layer capacitor is deteriorated, or the internal resistance of the capacitor is abnormally increased. As a countermeasure against this, by applying the embossing 21 to the leaded electrode plates 20a and 20b, it becomes possible to effectively apply pressure to the insulating rubber 3 and the conductive plastic film 6.
This is disclosed in Japanese Utility Model Application No. 2-89257.

[0006]

In this conventional electric double layer capacitor, the embossments 21 provided on the leaded electrode plates 20a and 20b are merely slightly recessed on the outside of the element 1, and the other surfaces are not provided. Since it is formed in a flat state, when the capacitor is molded, a radial deviation easily occurs between the leaded electrode plates 20a and 20b and the element 1 as shown in FIG. If there is a gap between the two in this way, the insulating rubber 3
Are abutted against each other, pressure is not effectively applied, and reliability deteriorates. In addition, when the amount of deviation is large, there is a problem that part of the element 1 is exposed from the resin 7 or a void in the shape of a hole is generated during molding, resulting in poor appearance. An object of the present invention is to provide an electric double layer capacitor in which positional deviation between an electrode plate with leads and an element is prevented, reliability is improved, and appearance is improved.

[0007]

In the electric double layer capacitor of the present invention, at least one of the leaded electrode plates is formed with an emboss which is slightly larger than the outer shape of the device, and this embossing positions the device and the leaded electrode plate. Configure to do. In this case , the step formed on the peripheral edge of the leaded electrode plate as an emboss has a size smaller than the thickness of the basic cell forming the element . Further, it is preferable to form this step in a tapered shape.

[0008]

According to the present invention, the embossing prevents the displacement of the element and the leaded electrode plate, the pressure is suitably applied to the element to improve the reliability, and the displacement is the cause. Prevents appearance defects.

[0009]

Next, the present invention will be described with reference to the drawings. FIG. 1 shows a capacitor of the present invention, (a) is a front view, and (b) is a sectional view taken along the line AA. 2 shows the electrode plate with leads, (a) is a front view, and (b) and (c) are cross-sectional views taken along the line BB and CC. In FIG. 1, the capacitor is composed of an element 1 and a pair of leaded electrode plates 10 (10a, 10b). The leaded electrode plate 10 sandwiches the element 1 at a required pressure and is integrated with a molding resin 7. Is molded into. The element 1 has the same structure as the conventional electric double layer capacitor element 1 shown in FIG. Reference numeral 8 is a pressure pin hole.

As shown in FIG. 2, the leaded electrode plate 10 has a first embossment 11 having a diameter smaller than the outer diameter of the element 1 at the center thereof, and a first embossment 11 on the outside thereof. The second embossing 12 is concentrically formed and is slightly larger than the outer diameter of the element 1. The step 13 formed on the peripheral edge portion to form the second emboss 12 is made smaller than the thickness of the basic cell 2 when the element 1 is compressed by pressure,
Moreover, it is formed in a tapered shape. That is, the conductive plastic film 6 of each basic cell 2 is exposed on the side surface of the element 1 in which the basic cells 2 are laminated, and the step 13 of the second emboss 12 is larger than the thickness of the basic cell 2 when compressed. In this case, the conductive plastic film 6 of the basic cell 2 comes into contact with each other, and the contacted basic cell 2 is in a short-circuited state and does not function as a capacitor, resulting in an apparent reduction in the number of laminated layers. The step 13 is designed so as not to occur. Further, when the element 1 is compressed, the outer diameter of the element changes so as to increase, so that the step 13 is tapered to avoid contact at that time.

When a capacitor is molded using the electrode plate with leads having this structure, the element 1 is placed on one of the electrode plates with lead 10a, and the electrode with the other lead is placed thereon, as in the conventional case. The one covered with the plate 10b is set in a molding die. At this time, the second emboss 12 provided on one of the leaded electrode plates 10a prevents the element 1 from being displaced within the second emboss 12. Further, the positional deviation of the other leaded electrode plate 10 b with respect to the element 1 is also stored in the second emboss 12. Therefore, the positional deviation between the leaded electrode plates 10a and 10b and the element 1 can be surely prevented, the decrease in reliability, which has been caused by the positional deviation between the two, is improved, and the element is exposed due to insufficient resin around. It is possible to prevent the occurrence of voids and improve the appearance defect. Incidentally, the generation rate of defective products in the conventional capacitor was about 3%, but could be set to 0% by the present invention.

Here, in this embodiment, the assembly operation of placing the element 1 on one of the leaded electrode plates 10a and covering the other leaded electrode plate 10b on the other is performed outside the molding die. For this reason, the second embossing 12 is provided on both of the leaded electrode plates. However, when assembling in the molding die, there is little displacement when the upper leaded electrode plate 10b is covered. , The second embossing 1 according to the present invention only on the lower electrode plate 10a with leads.
2 may be provided. In the present invention, since the element 1 has a cylindrical shape, the first and second embossments 11,
Although the shape is 12 circles, it goes without saying that the effect of the present invention can be achieved by changing the shape of the element to a quadrangle or another shape depending on the element shape.

[0013]

As described above, according to the present invention, the electrode plate with lead is provided with the second embossing for positioning the device slightly larger than the outer diameter of the device. The gap can be eliminated. This allows
The insulating rubber of the element is effectively pressed to improve the reliability of the capacitor, and at the same time, it is possible to prevent the defective appearance due to the element exposure or insufficient resin around. Also,
Steps formed as embosses on the periphery of the electrode plate with leads
Is smaller than the thickness of the basic cells that make up the device,
Conductivity where the peripheral edge of the electrode plate is exposed on the peripheral surface of the basic cell
Reliable without any electrical shorts coming into contact with parts
It is possible to obtain a high-capacity capacitor.

[Brief description of the drawings]

FIG. 1 shows an embodiment of an electric double layer capacitor of the present invention, (a) is a front view and (b) is a sectional view taken along the line AA.

2 shows an electrode plate with leads used in the capacitor of FIG. 1, (a) is a front view, (b) is a sectional view taken along line BB thereof, FIG.
(C) is the CC sectional view taken on the line.

3A and 3B show a conventional electric double capacitor, in which FIG. 3A is a front view and FIG.

FIG. 4 is a partial cross-sectional view showing the internal structure of the element.

FIG. 5 is a diagram showing pressure dependence of internal resistance of an element.

[Explanation of symbols]

 1 Element 2 Basic Cell 3 Insulating Rubber 4 Porous Separator 5 Activated Carbon Paste Electrode 6 Conductive Plastic Film 7 Mold Resin 10 (10a, 10b) Leaded Electrode Plate 11 First Embossing 12 Second Embossing 13 Step

Claims (2)

(57) [Claims] 1. An electric double layer capacitor in which an electric double layer capacitor element is sandwiched between a pair of electrode plates with leads at a predetermined pressure, and these are resin-molded. At least one electrode plate with leads has an electric double layer capacitor element. Is formed slightly larger than the outer shape of the electric double layer capacitor element, and the electric double layer capacitor element and the electrode plate with lead are positioned by the embossing.
The step formed on the periphery of the leaded electrode plate is
It depends on the thickness of the basic cell that constitutes the electric double layer capacitor element.
The electric double layer capacitor is characterized by its smaller size . Wherein the step formed on the periphery of the lead with the electrode plates constituting the embossing, made by tapered claim 1 of the electric double layer capacitor.