JP2016012654A - Film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film capacitor including two capacitor elements which have metallikon electrodes on the upper and lower end faces and are vertically stored in a cylindrical case with bottom having an opening in the upper end face and to the opening of the case an external electrode terminal is provided, which is capable of solving the problems that, when the capacitor elements are electrically connected in parallel, the impedance and equivalent series resistances tend to get higher at parallel resonance points due to parallel resonance, and a reflux current flows on a parallel circuit in the capacitor causing a large heat generation.SOLUTION: In order to connect the capacitor elements in parallel, the metallikon electrodes which are faced to each other between the capacitor elements are separated from each other via a spacer which has a higher portion and a lower portion and independently connected to the extraction electrode at the lower portion of the separator, and the extraction terminals thereof are connected to each other at the opening side of the case.

Description

  The present invention relates to a film capacitor.

Capacitor elements of film capacitors are made by winding or laminating films with thin film metal electrodes provided by vapor deposition. Metals such as zinc, copper or aluminum are attached to both end surfaces by metallicon (spraying), and the outside of the element An electrode (hereinafter referred to as a metallicon electrode) is formed.
In such a capacitor, the self-healing property of the capacitor element decreases when the deposited film thickness is increased to improve the conductivity value of the deposited film as an improvement to reduce the equivalent series resistance to reduce the loss and heat. As a result, the pressure resistance of the capacitor element decreases. For this reason, Patent Document 1 discloses a method in which one capacitor element is divided and at least two capacitor elements are connected in parallel as a method for shortening the distance to the metallicon electrode of the capacitor element without increasing the deposition film thickness. Is described.
However, when capacitor elements are connected in parallel, there is no problem in the capacitor guaranteed frequency region (1 kHz to 10 kHz), but in the high frequency region (20 KHz to), the impedance at the parallel resonance point and the equivalent series resistance are likely to increase due to parallel resonance. The problem is that a return current flows in the parallel circuit inside the capacitor, which causes a large amount of heat generation.
Therefore, in Patent Document 2, the capacitor elements are electrically connected in parallel, and the metallicon electrodes facing each other are separated from each other by a 50 μm-thick polyester sheet without being in direct contact with each other. A method has been proposed in which the lead terminals are connected to each other on the opening side of the case.

Japanese Utility Model Publication No. 7-29829 JP 2012-79757 A

  However, the opposing metallicon electrodes of the capacitor element are separated by a polyester sheet having a uniform thickness, and the opposing metallicon electrodes are connected separately to the lead terminals, and the lead terminals are connected to each other on the opening side of the case. When the is connected, the interval between the metallicon electrodes becomes longer by the amount of the connected lead terminals. For this reason, since the upper and lower capacitor elements are not aligned on the winding axis and are inclined, the inter-electrode distances are not uniform between the production lots, and there is a possibility that parallel resonance is likely to occur. In addition, since the upper and lower capacitor elements are tilted inside the case, the lead-out terminal will be close to the case even with an insulating sheet. If the case is made of metal, tightening pressure and case from the outside to fix the mounting legs Due to the collision at the time of insertion, the lead-out terminal and the insulating sheet become weak points locally and are easily short-circuited.

  The present invention suppresses the inclination between the upper and lower capacitor elements, reduces the impedance of the parallel capacitor resonance point and the increase in equivalent series resistance, suppresses the reflux current flowing in the parallel circuit inside the film capacitor, and generates heat of the film capacitor. The purpose is to suppress.

In order to solve the above problems, the present invention provides the following film capacitor.
(1) Two capacitor elements having a metallized electrode provided on both end faces and having an opening on the upper end face that accommodates the capacitor elements stacked in the winding axis direction are wound using a metallized film to form a cylindrical shape. A bottomed cylindrical case and a lead electrode connected to the metallicon electrode, wherein the capacitor elements are electrically connected in parallel, and the metallicon electrode facing the capacitor element has a height The separator is separated by a separator with a high part and a low part, and the separator is connected to the lead electrode separately at the low part of the separator, and the lead electrodes are connected to each other on the opening side of the case. Film capacitor.
(2) The film capacitor according to (1), wherein the spacer is provided with a through hole at least in a central portion.
(3) The film capacitor according to (1) or (2), wherein a partially thick portion of the spacer is a laminate portion.

  According to the present invention, there is provided a film capacitor in which two capacitor elements provided with metallicon electrodes on both end surfaces are stacked in the winding axis direction and accommodated in a bottomed cylindrical case having an opening on the upper end surface. To electrically connect the elements in parallel, they are separated by a spacer having a thick part and a thin part, and the thin part of the spacer is connected to the lead terminal separately. Since the lead terminals are connected to each other on the opening side of the case, the inclination between the upper and lower capacitor elements can be suppressed, and the increase in the impedance of the parallel capacitor resonance point and the equivalent series resistance can be sufficiently reduced. Therefore, the reflux current flowing in the parallel circuit inside the film capacitor can be suppressed, and the heat generation of the film capacitor can be suppressed.

1 shows a schematic cross-sectional view of a film capacitor of the present invention. 1 shows a schematic perspective view of a spacer of the present invention. Figure 4 shows a schematic perspective view of another spacer of the present invention. Figure 4 shows a schematic perspective view of another spacer of the present invention. Figure 4 shows a schematic perspective view of another spacer of the present invention. The schematic perspective view of the connection of the two capacitor | condenser elements of this invention and an extraction terminal is shown. Figure 4 shows a schematic perspective view of another spacer of the present invention.

  The metallicon electrode of the present invention is an element external electrode connected to the end of the electrode of the capacitor element, and can be prepared by attaching a metal such as zinc, copper, or aluminum by metallicon.

In the capacitor element of the present invention, a thin film metal electrode provided by vapor deposition is wound on a film, and element external electrodes (metallicon electrodes) in which metal is attached by metallicon are formed on both end faces. As the film, polyethylene terephthalate, polypropylene or the like can be used, and as the metal of the metal foil or thin film metal, aluminum, copper, zinc or an alloy thereof can be used.
The cross-sectional shape is circular, and when it is crushed, it becomes a flat shape. However, the flat shape has a flat side surface, which improves storage efficiency and heat dissipation.

The case of the present invention is a bottomed cylindrical container having an opening on the upper end surface and generally usable for a film capacitor, and can be formed of plastic or metal. If it is a plastic, for example, a resin such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, or polyphenylene sulfide may be used. As long as it is a metal, for example, aluminum, magnesium, iron, stainless steel, copper, or an alloy thereof can be used.
A capacitor element is provided in the case, most of which is filled with an insulating resin or the like. Insulating resin is an insulating material generally used for filling film capacitors, and is made by mixing a filler or the like with a resin such as epoxy resin or urethane resin. As the filler, hydroxides such as silicon, titanium, aluminum, calcium, zirconium, and magnesium, oxides, carbides, nitrides, and composites thereof can be used. If necessary, a flame retardant and an antioxidant may be added.

The lead terminal of the present invention is an electrode for connecting to a metallicon electrode and leading to the outside, a metal plate, metal foil or wire made of a metal or alloy such as copper, aluminum, iron, nickel, stainless steel, phosphor bronze, etc. on the surface. In some cases, tin, solder, or the like is plated. Tin-plated copper is preferred. The thickness and shape are designed in consideration of allowable current, ESL (equivalent series inductance), strength, stress reduction, and the like required by the product.
When there is a sealing body at the opening of the upper end surface of the case, a lead terminal is connected to an external electrode terminal provided on the sealing body so as to penetrate between the outer surface and the inner surface.

The spacer according to the present invention provides a gap between the metallicon electrodes facing each other of the two capacitor elements, and has a high portion and a low portion, and each of the low portion has a separate lead terminal and metallicon electrode. And connect. The difference in height between the high part and the low part is 1 mm to 10 mm, and the thickness of the thin part of the spacer itself is about 0.1 mm to 1 mm.
When the metallized film is wound by the winding core of the winding machine, the capacitor element has a columnar space after removing the winding core in the center. It is preferable that the filling resin that has flowed in through the columnar space easily flows in the direction of the lower capacitor element through the through hole of the spacer.
In addition, it is preferable to use a laminate structure to provide a part having a high height in the spacer, which can be manufactured at a lower cost than a molded product using a mold.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic cross-sectional view of the film capacitor of the present invention.
The two capacitor elements 1 are each formed into a cylindrical shape by winding using a metallized film, provided with metallicon electrodes 2 on both end surfaces, vertically stacked in the winding axis direction, and having a bottomed cylindrical shape having an opening on the upper end surface. It is housed in the case 3. The lead terminals 4 are connected to the respective metallicon electrodes 2 and are led out to the opening side of the case 3 so that the lead terminals 4 do not contact each other. The same poles are connected.
In addition, an insulating spacer 5 is sandwiched between the metallicon electrodes 2 facing each other between the pair of capacitor elements 1 so as not to directly contact each other. The spacer 5 has a high portion 5 a and a low portion 5 b, and the low portion 5 b is connected to the lead terminal 4 and the metallicon electrode 2, respectively.
The difference in height between the high part 5 a and the low part 5 b of the spacer 5, that is, the difference in level difference, is that when the connection between the lead terminal 4 and the metallicon electrode 2 is performed by solder connection, a raised part 6 is formed by solder. The lead terminal 4 is provided with a thickness larger than the sum of the height of the raised portion 6 due to the solder.

  FIG. 2 shows a schematic perspective view of the spacer of the present invention. The shape is an integrally formed disc shape, with the high portion 5a and the low portion 5b having a step on the front surface and the back surface, and the thickness on one side is reduced as a spacer.

FIG. 3 shows a schematic perspective view of another spacer of the present invention.
The shape is an integrally formed disc shape, and the height is low in both the upper and lower surfaces in one direction, and through holes 7 are provided in some places. The through hole 7 is provided so that the filling resin can be easily filled when the filling resin is injected into the case. In particular, when the capacitor element is wound around the metallized film by the winding core of the winding machine, Since the columnar space 8 (see FIG. 1) after the winding core is removed is formed, the filling resin that has flowed through the columnar space 8 of the capacitor element 1 passes through the through hole 7 of the spacer 5, This is preferable because it tends to flow in the direction of the lower capacitor element 1.

  FIG. 4 shows a schematic perspective view of another spacer of the present invention. As for the shape, a plurality of convex portions 9 are provided on a disc having a uniform thickness in an intermittent manner. The portions of the plurality of convex portions 9 are high height portions. By providing the plurality of convex portions 9 intermittently on the disk, the filler resin is easily filled into the spacer portion when the filler resin is injected into the case. Moreover, even if a groove is provided in the high portion of FIG. 2 or FIG. 3, the filling resin is easily filled in the spacer portion in the same manner.

  FIG. 5 shows a schematic perspective view of another spacer of the present invention. A uniform sheet having another thickness is laminated on a part of the uniform sheet. The laminate may be provided with an adhesive layer or a welding layer in the middle. The method of providing the high portion 5a by the laminating method is preferable in that respect because a molding die such as integral molding is unnecessary.

FIG. 6 shows a schematic perspective view of the connection between the two capacitor elements and the lead terminal of the present invention.
The two capacitor elements 1 are each wound using a metallized film to form a cylindrical shape. Metallicon electrodes 2 are provided on both end faces, and are stacked vertically apart in the winding axis direction. The lead terminal 4 is formed by punching a metal that can be bent into a U shape, the tip portion thereof being connected to the metallicon electrode 2, and being drawn out from the middle portion.

  FIG. 7 shows a schematic perspective view of another spacer of the present invention. This spacer has a shape in which the area of the portion 5b having a low height is reduced and shifted up and down in accordance with the structure of the lead terminal 4 in FIG. With this shape, the area of the high portion 5a of the spacer is increased, and the upper and lower capacitor elements are easily aligned on the winding shaft.

  DESCRIPTION OF SYMBOLS 1 ... Capacitor element, 2 ... Metallicon electrode, 3 ... Case, 4 ... Lead-out terminal, 5 ... Spacer, 5a ... High part, 5b ... Low part, 6 ... Swelling part by solder, 7 ... Through-hole, 8 ... Columnar space , 9 ... convex portion

Claims (3)

  Two capacitor elements with metallized electrodes provided on both end faces, and a bottomed cylinder with an opening on the upper end surface that accommodates the capacitor elements stacked in the direction of the winding axis. And a lead electrode connected to the metallicon electrode, the capacitor elements are electrically connected to each other in parallel, and the metallicon electrode facing the capacitor element has a high portion, They are separated by a separator having a low part, and are connected to the extraction electrode separately at the low part of the separator, and the extraction electrodes are connected to each other on the opening side of the case. Film capacitor.   The film capacitor according to claim 1, wherein the spacer is provided with a through hole at least in a central portion.   The film capacitor according to claim 1 or 2, wherein a part of the spacer which is partially high is a laminate part.

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