JP2006059890A - Dry capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry capacitor with which sufficient radiation effect is obtained with a simple structure. <P>SOLUTION: A capacitor element 1 is covered with first resin 5, and second resin 6 with larger thermal conductivity than first resin 5 is charged on first resin 5. The capacitor element 1 is provided with a winding core 2 having a space inside. Second resin 6 is injected inside the winding core 2. The winding core 2 has a projection part 2a projected upward. First resin 5 is charged to the middle of the projection 2a, and second resin 6 is charged on it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dry capacitor in which a capacitor element is housed in a case and filled with resin.

Conventionally, an epoxy resin having good flame resistance and insulating properties has been used as a sealing resin for dry capacitors. In addition, as a countermeasure for improving the moisture resistance of a capacitor and preventing cracks in a resin, a structure in which a low-hardness urethane resin and a high-hardness urethane resin have a double structure is known (for example, see Patent Document 1).
Japanese Patent Publication No. 63-51528

  By the way, in the case of a capacitor used with a large current, it is necessary to improve heat dissipation to prevent the capacitor from becoming high temperature. On the other hand, in the conventional capacitor, an epoxy resin, a urethane resin, or the like is used as the filling resin, but the thermal conductivity of these general plastic resins is 0.1 to 0.3 [W / (M · K)] and not so large that it is difficult to further improve the heat dissipation effect.

  The present invention has been made to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a dry-type capacitor having a simple structure and a good heat dissipation effect.

  The dry capacitor according to claim 1 is a dry capacitor in which the capacitor element 1 is housed in a case 4 and filled with a resin, and the capacitor element 1 is covered with a first resin 5 and the first resin 5 is covered with a second capacitor. The second resin 6 having a higher thermal conductivity than the first resin 5 is filled.

  The dry capacitor according to claim 2 is characterized in that the capacitor element 1 includes a core 2 having a space inside, and the second resin 6 is also injected into the core 2.

  In the dry capacitor according to claim 3, the core 2 has a protruding portion 2 a protruding upward from the metallicon electrode 7, and the first resin 5 is filled up to the middle of the protruding portion 2 a, and on the upper portion thereof. The second resin 6 is filled.

  The dry capacitor of claim 4 is characterized in that the lower end 2b of the core 2 is closed.

  The dry capacitor according to claim 5 is characterized in that the core 2 is made of metal.

  According to the dry capacitor of the first aspect, since the second resin 6 having a high thermal conductivity is filled on the opening side of the case 4, the heat generated by the capacitor element 1 can be radiated well.

  According to the dry type capacitor of the second aspect, since the resin 6 having a high thermal conductivity is filled in the core 2, the heat generated in the capacitor element 1 can be radiated well.

  According to the dry capacitor of the third aspect, since the first resin 5 is filled up to the middle of the upper protruding portion 2a of the core 2, the capacitor element 1 is substantially entirely extended up to the upper metallicon electrode 7. Is covered with the first resin 5, and the improvement effects such as flame retardancy and insulation by the first resin 5 can be secured.

  According to the dry type capacitor of the fourth aspect, since the core opening of the lower end 2b of the core 2 is filled and closed, the infiltration of the first resin 5 is prevented and the thermal conductivity is reduced. The large second resin 6 can be filled to the lower inside of the core 2, and the heat dissipation effect by the second resin 6 having a high thermal conductivity can be further improved.

  According to the dry capacitor of claim 5, since the heat dissipation effect of the metal core 2 is excellent, the heat generated inside the capacitor element 1 can be efficiently dissipated and is particularly effective as a large current capacitor.

  Next, specific embodiments of the dry capacitor of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which a capacitor element 1 is housed in a case 4 such as PBT (polybutylene terephthalate) resin, an epoxy resin 5 is placed on the lower side, and a thermal conductivity is placed on the upper side. The resin 6 is filled. As shown in FIG. 2, the capacitor element 1 is formed by winding a metallized film around a core 2 and spraying metal on the end face to form metallicon electrodes 7, 8. One end of the core 2 (upper end) ) Protrudes upward from the metallicon electrode 7 to form a protruding portion 2a. The other end (lower end) 2b of the core 2 is positioned substantially on the same plane as the metallicon electrode 8, and, for example, a filling is inserted into the core opening so that resin does not enter from the outside (see FIG. Not shown).

  Such a capacitor element 1 is housed in the case 4 so that the protruding portion 2a at one end of the core is located on the opening side of the case 4, and first, the flame-retardant epoxy resin 5 is filled. As shown in FIG. 1, the epoxy resin 5 is filled up to the middle of the protruding portion 2 a of the core 2 so that the metallized film and the metallicon electrodes 7 and 8 are covered. At this time, since the core opening of the other end (lower end) 2b of the core 2 is filled, the infiltration of the epoxy resin is prevented. Next, after the epoxy resin 5 is cured, the thermally conductive resin 6 is filled. The thermally conductive resin 6 is injected into the core 2 from the core opening of the protrusion 2 a and is filled so as to cover the opening of the case 4. The heat conductive resin 6 is a highly heat conductive resin such as heat-dissipating grease, and has a thermal conductivity of about 1 to 5 [W / (m · K)], which is an order of magnitude larger than an epoxy resin. Terminals 9 and 10 connected to the metallicon electrodes 7 and 8 are drawn out from the opening of the case 4.

  In the dry capacitor, since the resin 6 having a high thermal conductivity is filled on the opening side of the case 4, the heat generated by the capacitor element 1 can be radiated well. Further, since the inside of the core 2 is filled with the resin 6 having a high thermal conductivity, the heat generation inside the capacitor element 1 can be radiated well. Furthermore, since the epoxy resin 5 is filled partway along the upper protruding portion 2 a of the core 2, the capacitor element 1 is almost entirely covered with the epoxy resin 5 until reaching the upper metallicon electrode 7. The improvement effect of flame retardance, insulation, etc. by the epoxy resin 5 can be ensured. Further, since the core opening of the lower end 2b of the core 2 is filled and closed, the infiltration of the epoxy resin 5 is prevented, and the heat conductive resin 6 is filled to the lower side inside the core 2. In addition, the heat dissipation effect by the heat conductive resin 6 can be further improved.

  A plastic resin can be used as the core 2, but a metal (for example, a copper core) can be used to improve heat dissipation. When the metal core 2 is used, an insulation film 3 such as PP (polypropylene) is provided between the metal core 2 and the metallized film to ensure insulation. Such a dry capacitor is useful as a capacitor for a large current because the heat dissipation effect of the metal core 2 is excellent. For example, as shown in FIG. 3, when a plurality of capacitor elements (two or more) as described above are connected in parallel and housed in the case 4 and sealed with resin, the heat dissipation effect of the metal core 2 is excellent. Therefore, the heat generated inside the capacitor element 1 can be efficiently radiated, which is particularly effective. Capacitors are excellent in heat dissipation and can be used in places with high ambient temperatures.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, a vapor deposition film with a security mechanism may be used for the capacitor element. The epoxy resin 5 may be a urethane resin or the like. Further, the heat conductive resin 6 may be in a gel form or a solid form.

It is a center longitudinal cross-sectional view of one Embodiment of the dry type capacitor of this invention. It is a perspective view of the capacitor element used in the above. It is a center longitudinal cross-sectional view which shows other embodiment of the dry type capacitor of this invention.

Explanation of symbols

  1 .. Capacitor element, 2 .. Core, 3 .. Insulating film, 4. Case, 5 .. Epoxy resin, 6 .. Thermally conductive resin, 7, 8 ... Metallicon electrode, 2 a. Department.

Claims (5)

  A dry capacitor in which a capacitor element (1) is housed in a case (4) and filled with a resin. The capacitor element (1) is covered with a first resin (5), and the top of the first resin (5) is covered. A dry capacitor, wherein the second resin (6) having a thermal conductivity higher than that of the first resin (5) is filled.   The capacitor element (1) includes a winding core (2) having a space therein, and the second resin (6) is also injected into the winding core (2). Dry capacitor.   The winding core (2) has a protruding portion (2a) protruding upward from the metallicon electrode (7), and fills the first resin (5) halfway along the protruding portion (2a). The dry capacitor according to claim 2, wherein the second resin (6) is filled thereon.   The dry capacitor according to claim 2 or 3, wherein the lower end (2b) of the winding core (2) is closed.   The dry capacitor according to any one of claims 2 to 4, wherein the winding core (2) is made of metal.