JP2000243669A - Capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor having a structure in which the internal resistance can be reduced with good reproducibility and stability. SOLUTION: A capacitor element 2, where a couple of electrode foils are wound around a coiling axis 4 via electrically-insulating separator that can hold electrolyte, is accommodated with a bottomed cylindrical external loading case 5 together with the coiling axis 4 to seal the opening end of the external loading case 5 with a sealing member 6, and the side surface of the external loading case 5 is suitably deformed toward the inside of case, to form a recess 11 that pushes the capacitor element 2 towards the center of capacitor element 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor element in which a pair of electrode foils are wound via an electrically insulating separator capable of holding an electrolytic solution, and is housed in an outer case having a bottomed cylindrical shape. The present invention relates to a capacitor whose part is sealed with a sealing member.

[0002]

2. Description of the Related Art Conventionally, a capacitor element formed by winding a pair of electrode foils through an electrically insulating separator capable of holding an electrolytic solution is housed in an outer case having a bottomed cylindrical shape, and the opening end thereof is sealed. As a capacitor sealed with a member, the surface of a metal foil made of a valve metal such as aluminum is subjected to surface treatment for enlarging the surface area and an anodic oxidation is performed to form an oxide film as a dielectric layer. Foil and a cathode foil obtained by subjecting the surface of a metal foil made of a valve metal such as aluminum to only the above-mentioned wide-area embedding as a pair of electrode foils, and an electrolytic paper impregnated with an electrolytic solution is used as the electrical insulating separator. As an electrode using an electrolytic capacitor element formed by being wound between the anode foil and the cathode foil, or by forming an activated carbon layer on both sides of a metal foil made of a metal such as aluminum, and forming a polarizable electrode. With foil Is to use an electric double layer capacitor element formed by winding with intervening electrolyte sheet in which the electrolytic solution is impregnated between the polarizable electrode foils and a pair as electrically insulating separator.

[0003] The electric double layer capacitor using the electric double layer capacitor element includes an electric resistance of the activated carbon layer formed on both surfaces of the polarizable electrode foil and an electrolytic solution used inside the electric double layer capacitor. And the internal resistance including the contact resistance of other components. Further, the electrolytic capacitor using the electrolytic capacitor element also has an internal resistance including the electric resistance of the electrolytic solution used therein and the contact resistance of other components.

[0004] The internal resistance of these capacitors consumes charging current when charging the capacitors, and is released as thermal energy. Therefore, the energy stored in the capacitor is equal to the total charge energy input to the capacitor minus the energy lost as heat due to the internal resistance of the capacitor. Further, the discharge as heat energy due to the internal resistance is caused by the internal current of the capacitor which is consumed by the internal resistance as in the case of the charging current with respect to the discharge current at the time of discharging from the capacitor. The energy that is subtracted from the heat energy lost by the resistance is released to the outside. As described above, the internal resistance of the capacitor makes the discharge energy smaller than the charging energy applied to the capacitor and causes a decrease in energy efficiency. It is proportional to the magnitude of the internal resistance of the capacitor.

[0005] In particular, the electric double layer capacitor is expected to be used as a storage component of electric energy such as a substitute for a battery, and the decrease in energy efficiency at the time of charging and discharging is not preferable. Therefore, in the field of electric double layer capacitors, it is strongly desired to reduce the internal resistance.

Also, in the field of electrolytic capacitors, it has become an important problem to suppress the heat generated by the internal resistance in the recent trend toward higher ripples. Is required.

As a method of reducing the internal resistance of these capacitors, the present inventors have previously described Japanese Patent Application No. 10-31.
No. 6870, there is proposed a method of appropriately pressing and deforming the side surface of the outer casing housing the capacitor element inside the outer casing and compressing the accommodated capacitor element toward the center thereof. are doing.

According to this method, the internal resistance can be easily reduced by compressing the capacitor element toward the center thereof to reduce the distance between the pair of opposing electrode foils. In the electric double layer capacitor element, the activated carbon used for the polarizable electrode foil is a porous material having elasticity, so that applying pressure to the activated carbon increases the frequency of contact between the activated carbon and the activated carbon. Since the number of conductive paths in the inside increases, the electric resistance of the entire activated carbon layer can be reduced.

[0009]

However, in the proposed method, like the conventional capacitor element,
Since the center of the capacitor element is hollow, the capacitor element itself is easily deformed, so even if the deformation from the side of the exterior case is performed along a predetermined path,
There is a problem that a desired pressure toward the center direction may not be properly applied to each electrode foil, and a stable reduction in internal resistance with good reproducibility may not be obtained.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and has as its object to provide a capacitor having a structure capable of obtaining a stable reduction in internal resistance with good reproducibility.

[0011]

In order to solve the above-mentioned problems, a capacitor according to the present invention comprises a pair of electrode foils wound around a winding shaft via an electrically insulating separator capable of holding an electrolyte. The element is housed in a bottomed cylindrical outer case together with the winding shaft, the open end of the outer case is sealed with a sealing member, and the side of the outer case is appropriately deformed to the inside of the case to center the capacitor element. It is characterized in that a concave portion for pressing in the direction is formed. According to this feature, since the capacitor element is housed in the outer case in a state where the winding shaft exists at the center thereof, the concave portion is formed by appropriately deforming the side surface of the outer case to the inside of the case. Thereby, the electrode foil constituting the capacitor element is sandwiched between the concave portion and the winding shaft, and the pressure due to the deformation is stably applied to the electrode foil. Not only can the internal resistance be reduced, but the pressure applied to these electrode foils will be stable for a long time,
It is also possible to suppress the increase in the internal resistance during long-term use.

In the capacitor according to the present invention, the capacitor element is a polarizable electrode foil in which the electrode foil has an activated carbon layer on both surfaces thereof, and an electrode formed at an interface between the polarizable electrode foil and the electrolytic solution. It is preferable that the capacitor element uses a double layer. In this way, the pressure applied to the activated carbon can be made higher than that of the conventional one, and the resistance in the activated carbon can be made lower, and these pressures can be increased for a long time. Because it can be kept across, it is also possible to keep the increase in resistance of the activated carbon in long-term use low.

[0013] In the capacitor of the present invention, it is preferable that the concave portion is formed at a position substantially symmetrical with respect to a center axis of the capacitor. With this configuration, the pressure applied by the deformation is offset, so that the load applied to the winding shaft can be reduced, and defects such as warpage and bending of the winding shaft can be reduced.

[0014] In the capacitor of the present invention, it is preferable that the deformation for forming the concave portion is performed by a plurality of pressing jigs that press the side surfaces of the outer case almost simultaneously.
With this configuration, since the deformation is performed almost simultaneously and symmetrically, not only the displacement of the capacitor element and defects due to the deformation can be reduced, but also the applied pressure in the deformation can be reduced to the strength of the winding shaft. It can be made relatively high without depending on it, and the processing time in forming the concave portion can be shortened.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example in which the present invention is applied to an electric double layer capacitor will be described. However, the present invention is not limited to this, and the present invention is also applicable to the electrolytic capacitor. Can be.

(Embodiment) FIG. 1A is a side sectional view showing a capacitor of the present embodiment, and FIG.
FIG. 2A is a cross-sectional plan view of the capacitor of the present embodiment at A, and FIG. 2 is an external view showing the capacitor of the present embodiment.

The capacitor of this embodiment is an electric double layer capacitor, and reference numeral 2 in FIG. 1 is an electric double layer capacitor element.

As shown in FIG. 3, this electric double-layer capacitor element (hereinafter abbreviated as capacitor element) 2 is composed of a pair of polarizable electrode foils 12 and 14 each having an activated carbon sheet 16 adhered to both sides of an aluminum foil 15. It is formed by winding around the hollow winding shaft 4 with an electrolytic paper 13 as an electrically insulating separator interposed between the polarizable electrode foils 12 and 14, and is formed in a columnar shape. Note that the capacitor element 2
The outermost circumference is covered by winding the electrolytic paper,
The polarizable electrode foil 12 or 14 is not exposed. In order to prevent the capacitor element 2 from unraveling, an anti-winding tape (not shown) is wound around the outermost periphery.

The capacitor element 2 is impregnated with a predetermined electrolytic solution, the electrolytic solution is held on the electrolytic paper 13, and the state in which the electrolytic solution is in contact with the polarizable electrode foils 12, 14. Is to be formed.

The aluminum foil 15 used in the present embodiment has a thickness of about 30 μm and functions as a collecting electrode, and also has polarizable electrode foils 12 and 14 required for the winding and the like. Has the required mechanical strength such as tensile strength. The thickness of the activated carbon sheet 16 used in this embodiment is 100 to 500 μm.
m, but here 150 μm
m is used.

The activated carbon layer is applied to the aluminum foil 15
The method of forming on both surfaces of the aluminum foil 15 is not limited to the method of attaching the activated carbon sheet 16 to the aluminum foil 15 as described above. For example, a predetermined alcohol or the like is used as a binder, and activated carbon powder is mixed and kneaded. The paste may be applied to both sides of the aluminum foil 15 and dried to form an activated carbon layer on both sides of the aluminum foil. A method for forming these activated carbon layers may be appropriately selected.

An electrode tab 3 is connected to the aluminum foil 15 constituting the polarizable electrode foils 12 and 14 by a method such as cold welding or ultrasonic welding. From the winding end surface.

The hollow reel 4 used in this embodiment is
Is housed in the bottomed cylindrical outer case 5 together with the capacitor element 2 formed by winding, and is made of aluminum and has a predetermined thickness so as to have appropriate strength. The inner space of the cylinder is formed in a fitting projection 18 provided at the center of the bottom of the outer case 5 and a bake plate 7 fixed to close the opening end of the outer case 5. By fitting with the fitting projection 19, the capacitor element 2 is housed and fixed at a substantially central position inside the outer case 5.

The material used for these winding shafts is not limited to the above-mentioned aluminum, but may be a resin or the like, and may be appropriately selected in accordance with the strength or the like. The heat in the central portion of the capacitor element 2 is
It is also preferable because heat is radiated outside the capacitor.

Although the winding shaft of the present embodiment is hollow for fitting with the fitting projection 18 when housed in the outer case 5 as described above, the present invention is not limited to this. Instead, these winding shafts may be rod-shaped.

The capacitor element 2 is housed in an outer case 5 together with a sealing member 6, and the sealing member 6 has a structure in which an elastic member 8 such as rubber is bonded to an insulating hard bake plate 7. Two rivets 9 for electrically connecting the front and back of the sealing member 6 are provided so as to penetrate. A capacitor element 2 is provided on the inner side of the rivet 9.
Are connected by means of welding or the like, and an external head for obtaining an electrical and mechanical connection with the outside is provided on the external head of the other rivet 9. Terminal 10 is connected. The hard bake plate 7 has the fitting projection 19 formed at the center thereof as described above, and the sealing member 6 is used with the bake plate 7 side facing the inside of the outer case 5. You.

The outer case 5 used in this embodiment is made of a metal such as aluminum, and has an inner diameter slightly larger than the outer diameter of the capacitor element 2 and has a cylindrical shape having one open end. When the fitting projection 18 is inserted and fitted into the hollow winding shaft 4 and the capacitor element 2 is housed, the inner surface of the outer case 5 and the capacitor element 2 are formed. There is almost no gap between them.

Next, a fitting projection 19 provided on the bake plate 7 constituting the sealing member 6 is inserted and fitted into the other end of the hollow winding shaft 4 of the housed capacitor element 2 so as to fit therewith. And the sealing member 6 are stored. The outer case 5 in which the housing is accommodated is subjected to the lateral groove processing from the side surface and the curling processing of the opening end, thereby closing the opening end. By performing lateral groove processing from the side surface of the outer case 5 and curling of the opening end, the sealing member 6 is formed.
Is pinched between the lateral groove from the side surface and the tip of the curling portion, thereby performing positioning and preventing rotation. Further, in the curling process, by making the opening end of the outer case 5 bite into the elastic member 8 on the outer surface of the sealing member 6, the elastic member 8 and the opening end come into close contact with each other, and the inside of the outer case 5 becomes tight. Sealed.

The electric double layer capacitor 1 formed as described above is further deformed so as to form a concave portion on the side surface of the outer case 5, and compresses the capacitor element 2. As shown in FIG. 4A and FIG.
7 is moved in the direction of the arrow in the figure and pressed almost simultaneously from eight directions that are symmetrical with respect to the cylindrical outer case 5, thereby pressing the side surfaces of the outer case 5.
The outer case 5 is deformed so as to form three groove-shaped concave portions 11 long in the vertical direction. As shown in FIG. 2, the electric double layer capacitor 1 after the deformation of the outer case has three groove-shaped concave portions formed in a straight line in the longitudinal direction of the outer case 5, and the three linear grooves are formed. Are formed in eight directions that are substantially symmetrical positions on the circumference, and a total of 24 groove-shaped recesses 11 are formed.

As described above, the concave portion 11 is formed from eight directions on the circumference.
Is to deform from a direction having a symmetrical positional relationship with respect to the center of the capacitor 1, the deformation stresses from the symmetrical positions are offset each other, and the deformation applied to the hollow winding shaft 4 is reduced. It is possible to relieve the stress, to prevent the capacitor element 2 from being deformed due to the deformation of the hollow winding shaft 4, and to evenly compress the capacitor element 2 from a symmetric direction. However, the present invention is not limited to this, and the positions at which the concave portions are formed by these deformations are not symmetrical. For example, the concave portions are formed at every angle 120 on the circumference and three directions are formed. The concave portions 11 may be arranged so as to be balanced with each other, and the formation positions of these concave portions 11 may be appropriately selected.

Further, pressing the deforming jig 17 almost at the same time as described above allows the pressure to be efficiently applied to the capacitor 1 in the deformation, and the pressure can be applied in a short time. It is preferable because the processing time in the deformation processing can be reduced, but the present invention is not limited to this.

The form of applying pressure to the capacitor element 2 by deforming the side surface of the outer case 5 to form the recess 11 is limited to the form, number and arrangement of the recesses described above. Not something. For example,
As shown in FIG. 5 as a second embodiment, lateral grooves are formed on the side surface of the outer case instead of the vertical groove-shaped concave portions of the outer case 5 to form a plurality of rows of the horizontal groove-shaped concave portions 11 ′. The outer case 5 may be deformed to compress the capacitor element 2. The lateral groove processing here can be performed by the same method as the lateral groove processing performed when the opening of the outer case is sealed.

As described above, instead of deforming the outer case 5 so as to form the plurality of recesses 11, FIG.
As shown in the third embodiment, a wide lateral groove may be formed in the side surface of the outer case to deform the concave portion so as to form one concave portion 11 ″. Therefore, the compressed area of the side surface of the capacitor element 2 is increased, and the area of the activated carbon layer to be compressed is also increased.
The effect of reducing the electrical resistance of the activated carbon layer is great. Therefore, the effect of reducing the internal resistance of the capacitor also increases.

As described above, according to the present embodiment, the capacitor element 2 is housed in the outer case 5 while holding the hollow winding shaft 4 to form the capacitor 1, and the side surface of the outer case 5 is deformed by a jig. 17 to form the concave portion 11, the polarizable electrode foils 12 and 14 wound around the capacitor element 2 are sandwiched between the concave portion 11 and the hollow winding shaft 4, The capacitor element 2 can not only obtain a stable decrease in internal resistance with good reproducibility without excessive deformation, but also maintain these pressures for a long period of time. Can also be kept low.

Although the present invention has been described with reference to the drawings, the present invention is not limited to these embodiments, and changes and additions may be made without departing from the spirit of the present invention. Needless to say, it is included in the invention. For example, various forms other than the forms described above are conceivable. Within the scope of the present invention, any number of recesses may be used, and the shape and size of the recesses, the arrangement of the recesses, and the like can be arbitrarily selected. For example, it is possible to compress the capacitor element by forming one groove-shaped recess in the longitudinal direction of the outer case.

In the above embodiment, the electric double layer capacitor has been described. However, the present invention is not limited to this, and one of the polarizable electrode foils 12 and 14 can be made to increase the surface area of the aluminum foil 15. An anode foil that has been subjected to anodization along with the surface enlargement process, and an aluminum foil 15 that has been subjected to the surface enlargement as an electrolytic capacitor element, similarly to the electric double-layer capacitor, deforms the outer case to form a capacitor element. By compressing, by narrowing the distance between the anode foil and the cathode foil, it is possible to reduce the electrical resistance of the electrolytic solution held between them, with the effect of reducing the internal resistance of the electrolytic capacitor The stable decrease in the internal resistance can be obtained with good reproducibility, and the increase in the internal resistance during long-term use can be suppressed.

[0037]

The present invention has the following effects.

(A) According to the first aspect of the present invention, since the capacitor element is housed in the outer case with the winding shaft at the center thereof, the side surface of the outer case is directed toward the inside of the case. By forming a concave part by appropriately deforming,
Since the electrode foil constituting the capacitor element is sandwiched between the concave portion and the winding shaft, the pressure due to the deformation is stably applied to the electrode foil. In addition to the reduction in the internal resistance, the pressure applied to these electrode foils becomes stable over a long period of time, so that the increase in the internal resistance during long-term use can be suppressed.

(B) According to the invention of claim 2, the pressure applied to the activated carbon can be made higher than that of the conventional one, and the resistance of the activated carbon can be made lower. Not only can these pressures be maintained over a long period of time, but also the rise in resistance of the activated carbon during long-term use can be kept low.

(C) According to the third aspect of the present invention, since the applied pressure is canceled by the deformation,
The load applied to the winding shaft can be reduced, and defects due to warpage or bending of the winding shaft can be reduced.

(D) According to the fourth aspect of the present invention, since the deformation is performed symmetrically at substantially the same time, not only the displacement of the capacitor element and the failure due to the deformation can be reduced, but also the deformation of the capacitor element can be reduced. The applied pressure can be made relatively high irrespective of the strength of the winding shaft and the like, and the processing time for forming the concave portion can be shortened.

[0042]

[Brief description of the drawings]

FIG. 1A is a side sectional view showing a capacitor according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along an arrow in FIG.

FIG. 2 is an external view showing a capacitor according to an embodiment of the present invention.

FIG. 3 is an enlarged view showing a state of formation of a capacitor element and a configuration of a polarizable electrode foil used in an example of the present invention.

FIGS. 4A and 4B are schematic views showing a step of deforming the outer case in the embodiment of the present invention, wherein FIG. 4A is a front view and FIG. 4B is a top view.

FIG. 5 is an external view showing a capacitor according to another embodiment of the present invention.

FIG. 6 is an external view showing a capacitor according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 (Electric double layer) capacitor 2 (Electric double layer) capacitor element 3 Electrode tab 4 Hollow winding shaft 5 Outer case 6 Sealing member 7 Bake plate 8 Elastic member 9 Rivets 10 External terminal 11 Concave part 12 Polarized electrode foil 13 Electrical insulation Spacer 14 Polarized electrode foil 15 Aluminum foil 16 Activated carbon sheet 17 Deformation jig 18 Fitting protrusion 19 Fitting protrusion

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[Procedure amendment]

[Submission date] March 16, 1999 (1999.3.1.
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION The present invention, a pair of electrode foils, a capacitor element formed by winding via an electrically insulating separator capable of holding an electrolytic solution is housed in a bottomed cylindrical exterior case, the open end The present invention relates to a capacitor whose part is sealed with a sealing member.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

Conventionally, a pair of electrode foils, a capacitor element formed by winding via an electrically insulating separator capable of holding the electrolyte, housed in a bottomed cylindrical exterior case, sealing the open end As a capacitor sealed with a member, the surface of a metal foil made of a valve metal such as aluminum is subjected to surface treatment for enlarging the surface area and an anodic oxidation is performed to form an oxide film as a dielectric layer. Foil and a cathode foil obtained by subjecting the surface of a metal foil made of a valve metal such as aluminum to only the above-mentioned wide-area embedding as a pair of electrode foils, and an electrolytic paper impregnated with an electrolytic solution is used as the electrical insulating separator. As an electrode using an electrolytic capacitor element formed by being wound between the anode foil and the cathode foil, or by forming an activated carbon layer on both sides of a metal foil made of a metal such as aluminum, and forming a polarizable electrode. With foil Is to use an electric double layer capacitor element formed by winding with intervening electrolyte sheet in which the electrolytic solution is impregnated between the polarizable electrode foils and a pair as electrically insulating separator.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

[0011]

In order to solve the above-mentioned problems, a capacitor according to the present invention comprises a pair of electrode foils wound around a winding shaft via an electrically insulating separator capable of holding an electrolyte. around the element, as well as sealing the sealing member to the open end of the bottomed cylindrical outer instrumentation case by housing the exterior case together with the winding shaft, the said capacitor element by deforming appropriately sides of the outer case to the inner side of the case It is characterized in that a concave portion for pressing in the direction is formed. According to this feature, since the capacitor element is housed in the outer case in a state where the winding shaft exists at the center thereof, the concave portion is formed by appropriately deforming the side surface of the outer case to the inside of the case. Thereby, the electrode foil constituting the capacitor element is sandwiched between the concave portion and the winding shaft, and the pressure due to the deformation is stably applied to the electrode foil. Not only can the internal resistance be reduced, but the pressure applied to these electrode foils will be stable for a long time,
It is also possible to suppress the increase in the internal resistance during long-term use.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

The electric double layer capacitor 1 formed as described above is further deformed so as to form a concave portion on the side surface of the outer case 5, and compresses the capacitor element 2. Deformation of the side surface, as shown in FIG. 4 (a) and (b), deformation jig 1
7 is moved in the direction of the arrow in the figure and pressed almost simultaneously from eight directions that are symmetrical with respect to the cylindrical outer case 5, thereby pressing the side surfaces of the outer case 5.
The outer case 5 is deformed so as to form three groove-shaped concave portions 11 long in the vertical direction. As shown in FIG. 2, the electric double layer capacitor 1 after the deformation of the outer case has three groove-shaped concave portions formed in a straight line in the longitudinal direction of the outer case 5, and three groove-shaped concave portions on the straight line. Are formed in eight directions that are substantially symmetrical positions on the circumference, and a total of 24 groove-shaped recesses 11 are formed.

Claims (4)

[Claims] 1. A capacitor element in which a pair of electrode foils are wound around a winding shaft via an electrically insulating separator capable of holding an electrolytic solution, is housed together with the winding shaft in an outer case having a bottomed cylinder. A capacitor, wherein an open end of an outer case is sealed with a sealing member, and a side surface of the outer case is appropriately deformed toward the inside of the case to form a recess for pressing the capacitor element toward a center. 2. The capacitor element according to claim 1, wherein said electrode foil is a polarizable electrode foil having an activated carbon layer on both surfaces thereof, and uses an electric double layer formed at an interface between said polarizable electrode foil and said electrolytic solution. The capacitor according to claim 1, wherein the capacitor element is formed. 3. The capacitor according to claim 1, wherein the recess is formed at a position substantially symmetrical with respect to a center axis of the capacitor. 4. The capacitor according to claim 1, wherein the deformation for forming the concave portion is performed by a plurality of pressing jigs for pressing the side surfaces of the outer case almost simultaneously.