JP2010087318A - Capacitor module and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor module that is reduced in contact resistance and decreased in height by joining an external terminal and a bus bar together with ultrasonic welding, and to provide a method of manufacturing the same. <P>SOLUTION: In the capacitor module comprising a capacitor constituted by storing a capacitive element in an exterior case and sealing it by inserting into the opening of the exterior case a sealing member with the external terminal buried therein, and the bus bar constituted by electrically connecting external terminals of a plurality of capacitors to each other, the sealing member is formed integrally with the bus bar having one end welded to the external terminal and the other made open before being inserted into the opening, and after the sealing member is inserted into the opening, the other bus bar of another capacitor and the bus bar have other-end sides joined together. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a capacitor module and a manufacturing method thereof.

  A capacitor typified by an electric double layer capacitor has a large capacitance and is employed in an uninterruptible power supply (UPS) and the like. However, even a large-scale UPS has an electric double layer capacitor with a large electrostatic capacity, and one electric charge has a small charge, and a plurality of electric double layer capacitors are connected in series and / or in parallel to form a module. in use.

  As a configuration of such an electric double layer capacitor having a large capacitance, a plate-like electrode sheet in which polarizable electrode layers are formed on both sides of a current collector is used as a positive electrode sheet and a negative electrode sheet, and these are interposed via a separator. There is known an electric double layer capacitor having a configuration in which a capacitor element is formed by winding or alternately stacking, and the capacitor element is housed in an outer case made of aluminum or the like, and an opening end is sealed by a sealing member. Yes.

  Patent Document 1 and Patent Document 2 are known as technologies for modularizing such an electric double layer capacitor.

JP 2000-12383 A JP 2006-310490 A

  Currently, the bus bar for connecting the external terminals of a plurality of capacitors is fixed by screwing into a screw hole formed in the external terminal. In this fixing by screwing, electrical connection between the external terminal and the bus bar is achieved by mechanical contact with a screw. On the other hand, the electric double layer capacitor has a low withstand voltage of about 2.3 V to several V per capacitor. For this reason, the influence of the contact resistance at the contact portion between the external terminal and the bus bar becomes large.

  Thus, reducing the contact resistance between the external terminal and the bus bar is an important factor for improving the stored charge of the capacitor module.

  From this point of view, it is expected that the bus bar is joined to the external terminal by ultrasonic welding to reduce the height dimension and the contact resistance.

  However, the following problems occur when ultrasonic welding is simply performed when the external terminal of the capacitor is connected to another external terminal.

  When trying to weld a bus bar to an external terminal by ultrasonic welding, a bus bar is mounted on the external terminal and a horn for ultrasonic welding is contacted to perform ultrasonic welding. The energy of this ultrasonic vibration may escape and proper bonding may not be possible.

  This is because the structure of the capacitor employs a structure in which a sealing member is inserted into the opening of the outer case and crimped, so there is a slight gap between the outer case, the inner surface, and the sealing member. For lateral vibration applied from the sonic welding horn, the sealing member vibrates laterally inside the exterior case, and the energy of ultrasonic vibration is not sufficiently transmitted to the external terminal and bus bar of the sealing member. This is probably because of this.

  In addition, vibration stress during ultrasonic welding may be transmitted to the capacitor element, thereby adversely affecting electrical characteristics such as an increase in internal resistance of the capacitor.

  Accordingly, the present invention is to provide a capacitor module that reduces the contact resistance by joining the external terminal and the bus bar by ultrasonic welding, and also reduces the height of the entire capacitor module, and a method for manufacturing the same. .

  In order to solve the above-mentioned problem, a capacitor module according to the first provision of the present invention includes a capacitor element housed in an outer case, and a sealing member in which an external terminal is embedded in an opening of the outer case. A capacitor module comprising a capacitor and a bus bar formed by electrically connecting external terminals of a plurality of capacitors, the sealing member is connected to the external terminal before being inserted into the opening. One end is welded, and after the sealing member is inserted into the opening of the exterior case and sealed, another bus bar of the other capacitor and the bus bar are joined at the other end.

  The bus bar is a flat plate-like member and is connected in parallel with the sealing member of the capacitor.

  The manufacturing method according to the second prescription of the present invention includes a capacitor in which a capacitor element is housed in the outer case, and a sealing member in which an external terminal is embedded in the opening of the outer case is inserted and sealed. In the method of manufacturing a capacitor module comprising a bus bar formed by electrically connecting external terminals of the capacitor, the capacitor is sealed by a sealing member in which one end of the bus bar is welded to the outside of the external terminal in advance. A capacitor bank is configured by joining the other ends of the bus bars welded to the external terminals of these capacitors.

  As shown in the present invention, a capacitor element is housed in an exterior case, a sealing member in which an external terminal is embedded in an opening of the exterior case is inserted, and the sealed capacitor and the external terminals of a plurality of capacitors are connected to each other In the capacitor module constituted by a bus bar that is electrically connected, the sealing member is integrated with the bus bar that is welded at one end to the external terminal and opened at the other end before being inserted into the opening. After the sealing member is formed and inserted into the opening, another bus bar of the other capacitor and the bus bar are joined at the other ends, thereby reducing the contact resistance and mechanically performing ultrasonic welding. Stress is not transmitted to the inside of the capacitor.

  Further, if the bus bar is formed as a flat plate member and connected in parallel with the sealing member of the capacitor, a significant effect that the height dimension of the capacitor module can be reduced is brought about.

  As an outline of the structure of the electric double layer capacitor, as shown in FIG. 3, the capacitor element 1 in which the positive electrode sheets 11 and the negative electrode sheets 12 are alternately stacked via the separator 13 is housed in a metal outer case 3, The opening end of the case is sealed with the sealing member 2.

  Below, the manufacturing method of the electric double layer capacitor of this invention is demonstrated one by one.

  As shown in FIG. 2, the positive electrode sheet 11 and the negative electrode sheet 12 are flat electrode sheets in which polarizable electrode layers 14 and 14 mainly composed of activated carbon are formed on both sides of a current collector 13. The electrode arranged on the outermost part of the capacitor element may be one in which the polarizable electrode layer 14 is formed only on the inner surface.

  The positive electrode sheet 11 and the negative electrode sheet 12 are obtained by kneading activated carbon, carbon black as a conductive auxiliary agent, and polytetrafluoroethylene powder as a binder in a wet or dry manner to obtain a kneaded product. The kneaded material is solidified by applying to the electric body 13 and drying to form the polarizable electrode layers 14 and 14 on the current collector 13. Furthermore, you may press the polarizable electrode layers 14 and 14 so that it may become predetermined thickness with a rolling roll.

  In addition to the above steps, the kneaded product may be formed into a sheet and dried, and this sheet may be attached to a current collector with a conductive adhesive to produce a polarizable electrode. In this case, the thickness may be set to a predetermined thickness with a rolling roll in the state of the sheet, or the thickness may be set to a predetermined thickness with the rolling roll after the sheet is attached to the current collector.

  The current collector 13 can be a metal foil, mesh, or the like, rather than a metal, but it is 40 μm from the viewpoint of corrosion resistance to the electrolyte, conductivity of the current collector itself, and mechanical strength of the current collector. An aluminum foil having a thickness of about can be suitably used. In addition, when using aluminum foil, it is good to form the fine unevenness | corrugation in the surface by the etching process. If there are fine irregularities on the surface, the wettability is improved when the kneaded product is applied to the current collector or when a conductive adhesive is applied to the current collector, and the adhesion strength with the polarizable electrode layer is strong. It will be a thing.

  Further, a tab 15 for external drawing is connected to the current collector 13 in advance. The tab 15 is obtained by projecting a part of the current collector 13 from one side of the current collector 13. The tab 15 may be formed by connecting a member different from the current collector 13 to the current collector by a cold welt method, an ultrasonic welding method, or the like.

  As shown in FIG. 3, the positive electrode sheet 11 and the negative electrode sheet 12 are formed by alternately laminating a plurality of positive electrode sheets 11 and negative electrode sheets 12 with a separator 16 interposed therebetween. As the separator 16, a polypropylene nonwoven fabric or the like can be used. At this time, lamination is performed so that the positive electrode tabs and the negative electrode tabs overlap each other.

  Moreover, the winding tape 17 is wound around the outer periphery of these laminated bodies, and it fixes so that a laminated body may not loosen.

  Next, the tab derived from the capacitor element and the external terminal 21 of the sealing member 2 are electrically joined. The sealing member 2 is made of a hard resin, and elastic rubber is disposed on the outer peripheral portion of the upper surface, and is embedded so that the metal external terminals 21 and 21 pass therethrough.

  In this sealing member, a bus bar is ultrasonically welded in advance to the tip of an external terminal which is the outside of the capacitor. As the bus bar, an aluminum flat wire having a thickness of about 0.2 mm to 0.5 mm can be used.

  Then, the other end face of the external terminal of the sealing member is connected to the tab 15 drawn from the capacitor element 1. The connection method of the tab 15 and the external terminal 21 is not particularly limited, but one end of the connection lead is attached by overlapping a plurality of tabs, and the other end of the connection lead is connected to the inner end of the external terminal. The method can be taken.

  Then, the capacitor element 1 connected to the sealing member 2 is accommodated in the outer case 3. The outer case 3 has a prismatic shape, and one end is open. Aluminum or an aluminum alloy can be used as the material of the outer case 3. A lateral groove for positioning the sealing member is formed on the side surface in the vicinity of the opening end. Further, in order to increase the mechanical strength of the outer case, ribs that protrude from the inner side to the outer side may be provided.

  Then, as shown in FIG. 1A, the capacitor element 1 is accommodated in the outer case 3. Thereafter, as shown in FIG. 1B, the electrolytic solution 4 is injected into the outer case 18 and the capacitor element 1 is impregnated with the electrolytic solution. In FIG. 1, the tab of the capacitor element 1 is omitted.

The electrolytic solution used here is a solute composed of a cation such as a quaternary ammonium ion, an anion such as BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ or CF ₃ SO ₃ ^— , propylene carbonate, 1-butylene carbonate. An organic electrolytic solution composed of an aprotic solvent such as sulfolane, acetonitrile, γ-butyrolactone, dimethylformamide and the like is preferable. And as shown in FIG.1 (d), an electric double layer capacitor is completed by sealing the opening edge part of an exterior case with a sealing member.

  This sealing is performed by curling the opening end portion of the exterior case to seal the opening end portion. By curling the opening end of the outer case, the sealing member is sandwiched between the lateral groove formed on the side surface of the outer case and the tip of the curling portion, and positioning is performed. Further, in the curling process, the opening end portion of the outer case is bitten into the elastic rubber layer of the sealing member so that the elastic member and the opening end portion are in close contact with each other, thereby obtaining the airtightness of the electric double layer capacitor.

  Next, FIG. 5 shows a sectional view of the sealing member 2 and the external terminal 21 according to the present invention. Here, the external terminal 21 penetrates the sealing member 2 in a state where the sealing member 2 does not seal the exterior case 3. A flat bus bar 22 is connected to the upper end of the penetrated external terminal 21 by ultrasonic welding.

  Furthermore, when the flat bus bar 22 is ultrasonically welded to the upper end portions of the external terminals 21 of both electrodes as shown in FIG. 6, the sealing member 2 seals the outer case 3.

  Next, in order to connect the bus bars 22 to each other, FIG. The folding position 24 is bent at a position where the protrusion of the bus bar 22 becomes longer than the outer case 3. The bending direction is a direction away from the sealing member 2 and is bent perpendicular to a line connecting the two external terminals 21.

  Both ends of the bus bars 22 that are ultrasonically welded to the external terminals 21 of both poles are bent, but both end portions are bent with respect to the center of the outer case 3. For this reason, the bus bars 22 connected to the external terminals 21 of the same sealing member 2 are completely separated. Meanwhile, the bus bars 22 of adjacent capacitors are configured to be connected to each other. The bus bars 22 are connected to each other by ultrasonic welding. Since the connection between the bus bars 22 is away from the external terminal 21, the vibration stress during ultrasonic welding is transmitted to the capacitor element, thereby preventing adverse effects on electrical characteristics such as an increase in internal resistance of the capacitor. be able to.

  During curling, if the pre-welded bus bar is an obstacle to contacting the curling jig, the bus bar is bent once and the curling jig is brought into contact with the opening end side. it can.

  It will continue to be modularized. That is, the capacitors are connected to each other.

  Since the capacitor completed as described above is in a state where the bus bar is connected to the external terminal, the capacitor module is completed by joining the bus bars.

  Although the capacitor module is obtained by the above process, the above capacitor module is a structure that is joined only by the ultrasonic welding of the bus bar. Therefore, when mechanical stress is applied from the outside, the ultrasonic weld is peeled off. There is a risk of it. Therefore, as shown in FIGS. 8 and 9, a lower mold 44 having a plurality of recesses that match the external dimensions of the capacitor and two upper molds 40 and 42 for fixing the shoulder portion of the external terminal lead-out surface of the capacitor are used. The capacitor module can be reinforced by fixing the upper molds 40, 42 and the lower mold 44 with screws 46, or the like.

  In addition to the above, the capacitor module can be reinforced by various means such as a method of housing the capacitor module in a housing and filling it with resin.

It is sectional drawing of the electrical double layer capacitor exterior case 3 which concerns on this invention. It is a perspective view of the current collector 23 of the electric double layer capacitor according to the present invention. 1 is a perspective view showing a capacitor element of an electric double layer capacitor according to the present invention. It is the schematic of the structure of the electric double layer capacitor which concerns on this invention. It is the side view about the sealing member 2 and the external terminal 21 which concern on this invention. It is a block diagram of the bus bar welded to the sealing member 2 and the external terminal 21 which concern on this invention. It is a connection block diagram of the bus bar of the electric double layer capacitor according to the present invention. It is a longitudinal cross-sectional view of the housing of the electric double layer capacitor according to the present invention. It is a perspective view of the housing | casing of the electric double layer capacitor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Sealing member 3 Exterior case 4 Electrolyte solution 11 Positive electrode sheet 12 Negative electrode sheet 13 Current collector 14 Polarization electrode layer 15 Tab 16 Separator 17 Winding tape 18 Exterior case 21 External terminal 22 Bus bar 40, 42 Upper mold 44 Lower Type 46 screw

Claims (3)

The capacitor element is housed in a bottomed cylindrical outer case, a sealing member in which an external terminal is embedded in the opening of the outer case is inserted, and the capacitor is sealed,
In a capacitor module composed of bus bars formed by electrically connecting external terminals of a plurality of capacitors,
One end of the bus bar is welded to the external terminal before the sealing member is inserted into the opening,
A capacitor module configured by inserting the sealing member into the opening of the exterior case and sealing the joint, and then joining another bus bar of the other capacitor and the bus bar at the other ends.   The capacitor module according to claim 1, wherein the bus bar is connected in parallel with the sealing member. Capacitor element is housed in the outer case, a sealing member in which an external terminal is embedded in the opening of the outer case is inserted, and the capacitor is sealed,
In a method of manufacturing a capacitor module composed of bus bars formed by electrically connecting external terminals of a plurality of capacitors,
Capacitor sealing is performed by a sealing member in which one end of a bus bar is welded to the outside of the external terminal in advance,
A method of manufacturing a capacitor bank, which comprises a capacitor bank by joining the other ends of bus bars welded to external terminals of these capacitors.

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