JP5919489B2 - Case mold type capacitor - Google Patents

Description

  The present invention relates to a case mold type capacitor that is used in various electronic devices, electrical devices, industrial devices, automobiles, and the like, and is particularly suitable for driving a motor of a hybrid vehicle.

  In recent years, from the viewpoint of environmental protection, all electric devices are controlled by inverter circuits, and energy saving and high efficiency are being promoted. In particular, in the automobile industry, hybrid vehicles (hereinafter referred to as HEVs) that run on electric motors and engines have been introduced into the market, and the development of technologies relating to energy saving and high efficiency has been activated, which is friendly to the global environment.

  Since such an electric motor for HEV has a high operating voltage range of several hundred volts, a metalized film capacitor having high withstand voltage and low loss electric characteristics is attracting attention as a capacitor used in connection with this electric motor. In addition, the trend of adopting a metallized film capacitor having a very long life is conspicuous from the demand for maintenance-free in the market.

  By the way, when this metallized film capacitor is mounted on an HEV, it is inevitably exposed to severe temperature conditions and humidity conditions, and therefore it is essential to have high weather resistance. Accordingly, these metallized film capacitors are generally used as case-molded capacitors that are housed in a top-opening case, molded with a resin such as epoxy, and coated with a resin to increase the weather resistance.

  Specifically, the configuration of a conventional case mold type capacitor 101 shown in Patent Document 1 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the case mold type capacitor 101.

  As described above, the case mold type capacitor 101 has a structure in which a plurality of capacitor elements 103 which are metallized film capacitors are accommodated in a resin case 102 having an opening on the upper surface.

  Further, an epoxy resin is injected and cured as a mold resin 104 into the case 102. As described above, the capacitor element 103 is covered with the mold resin 104 to be protected from an external thermal shock and moisture intrusion.

  One end of the bus bar 106 is connected to a pair of electrodes 105a and 105b provided on both end faces of the capacitor element 103, respectively. The other end side of the bus bar 106 is exposed from the casting surface of the mold resin 104 filled in the case 102 and further drawn out to the outside of the case 102. That is, the capacitor element 103 is electrically connected to the outside by connecting the other end of the bus bar 106 to an external terminal of the case mold type capacitor 101.

  As described above, the case mold type capacitor 101 has a configuration in which the weather resistance is improved by using the capacitor element 103 in a state where the capacitor element 103 is coated with a resin having excellent heat resistance and moisture resistance such as epoxy resin.

JP 2008-130640 A

  Certainly, according to the above configuration, it is possible to improve the weather resistance by covering the capacitor element 103 with the mold resin 104, but this conventional case mold type capacitor 101 has the following problems. there were.

  That is, as shown in FIG. 3, the case mold type capacitor 101 has a configuration in which the bus bar 106 is provided in the vicinity of the inner wall of the case 102, but there is a place where the bus bar 106 is close to the case 102 in this way. The mold resin 104 may creep up the gap between the bus bar 106 and the case 102 due to a capillary phenomenon.

  If the mold resin 104 crawling up the gap adheres to the portion connected to the external terminal of the bus bar 106, the conduction between the capacitor element 103 and the external terminal will be hindered, which in turn will deteriorate the characteristics of the capacitor. Can be a cause.

  That is, suppressing the creeping of the mold resin 104 filling the case 102 directly leads to improvement of the reliability of the case mold type capacitor 101 as a capacitor, and the solution of this problem is very important. .

  Accordingly, an object of the present invention is to solve such problems and to provide a case mold type capacitor having excellent reliability.

In order to solve this problem, a case mold type capacitor of the present invention includes a case having an opening on the upper surface, a capacitor element housed inside the case and having a pair of end face electrodes at both ends, and the case. A mold resin that is injected and molds the capacitor element, and a pair of bus bars that have one end connected to the pair of end surface electrodes of the capacitor element and the other end exposed from the mold resin and connected to an external terminal, respectively. The bus bar is disposed along the inner side wall of the case and has a through hole partially embedded in the mold resin, and the capacitor element has the pair of end face electrodes at the inner side wall of the case. A plurality of bus bars are accommodated in the case so as to face each other, and the bus bar electrically connects the end face electrodes of the adjacent capacitor elements Connected to, the through hole is obtained by a structure which is arranged between the capacitor elements adjacent.

  According to the configuration of the present invention, the reliability of the case mold type capacitor can be enhanced.

  This is because the bus bar is provided with a through hole, and a part of the through hole is embedded in the mold resin.

  That is, by providing the through hole in the bus bar, the surface tension of the mold resin existing in the gap between the bus bar and the inner wall of the case is dispersed, and the capillary phenomenon is hardly generated.

  As a result, the creeping of the mold resin between the bus bar and the case inner wall can be suppressed, and the reliability of the case mold type capacitor can be improved.

The perspective view which shows the structure of the case mold type capacitor | condenser of this invention It is a figure which shows the structure of the case mold type capacitor | condenser of this invention, (a) is a perspective view after a mold, (b) is sectional drawing Sectional view showing the structure of a conventional case mold capacitor

  Hereinafter, the configuration of the case mold type capacitor 1 of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a state before injecting a mold resin 9 into the case 2 in the case mold type capacitor 1 of the present embodiment.

  As shown in FIG. 1, the case mold type capacitor 1 of the present embodiment has a mode in which a capacitor element 3 is accommodated in a case 2.

  Case 2 is a case formed of a resin. In this embodiment, polyphenylene sulfide (PPS) having particularly excellent heat resistance and impact resistance is used. As shown in FIG. 1, the case 2 has a box shape with an upper opening. For convenience of explanation, the upper direction in FIG. 1 is described as the upper direction of the case mold type capacitor 1 in this specification. However, in actual use, it is not always necessary to arrange the opening side as the upper direction. It is also possible to use in a state of being placed horizontally in the horizontal direction. Or it is also possible to use it in the state which orient | assigned the opening part to the perpendicular direction downward.

  A plurality of capacitor elements 3 are accommodated in the case 2. In this embodiment, six capacitor elements 3 are arranged in a line.

  The capacitor element 3 is formed by stacking a pair of two metallized films obtained by vapor-depositing aluminum on a polypropylene dielectric film, winding these metallized films a plurality of turns, and pressing them flatly. . Capacitor element 3 has end face electrode 4a and end face electrode 4b (not shown in FIG. 1 and shown in FIG. 2B) on both end faces. The end face electrode 4 a and the end face electrode 4 b are metallicon electrodes formed by spraying zinc on the winding end face of the capacitor element 3. In this embodiment, polypropylene is used as the dielectric film, but polyethylene terephthalate, polyethylene naphthalate, polyphenyl sulfide, polystyrene, or the like may be used in addition to polypropylene. Further, the metal to be deposited is not limited to aluminum, and tin, magnesium, or an alloy using a plurality of these metals may be used.

  As shown in FIG. 1, the capacitor element 3 is disposed in a horizontal state inside the case 2. That is, the plurality of capacitor elements 3 arranged in a line are accommodated in the accommodating portion of the case 2 in a state where the end surface electrodes 4 a and 4 b provided at both ends thereof face the inner surface of the side wall on the long side of the case 2. ing. The plurality of capacitor elements 3 are arranged so that end face electrodes in the same direction have the same polarity.

  A bus bar 5a and a bus bar 5b, which are members for electrically connecting the capacitor element 3 and the outside of the case mold type capacitor 1, are connected to the end face electrodes 4a and the end face electrodes 4b of the plurality of capacitor elements 3, respectively. . As shown in FIG. 1, the bus bar 5 a and the bus bar 5 b are disposed on the side wall on the long side of the case 2, and the gap 6 a and the gap 6 b are slightly opened and fixed along the side wall. The bus bar 5a, the bus bar 5b, and the case 2 are fixed by screwing a screw hole 7a (not shown in FIG. 1; shown in FIG. 2B) and a screw (not shown) into the screw hole 7b. . In this embodiment, the bus bar 5a and the bus bar 5b are made of copper.

  The end face electrodes 4a of the plurality of capacitor elements 3 accommodated in the case 2 are electrically connected to the bus bar 5a with solder or the like, and the end face electrodes 4b are electrically connected to the bus bar 5b. That is, the plurality of capacitor elements 3 are connected in parallel.

  One of the technical features of the present invention is that the bus bar 5a and the bus bar 5b are provided with circular through holes 8a and 8b (not shown in FIG. 1; shown in FIG. 2B). is there. These through-holes 8a and 8b are provided above the adjacent capacitor element 3 as shown in FIG. However, in this embodiment, as described above, the capacitor element 3 has a flat shape, and the lower end portions of the through hole 8a and the through hole 8b are located between adjacent curved portions of the flat capacitor element 3. positioned. Further, as shown in FIG. 1, the through hole 8 a and the through hole 8 b are arranged between the capacitor elements 3 so as not to overlap with the capacitor element 3. The effects of the through holes 8a and 8b will be described later.

  Next, the case mold type capacitor 1 after the mold resin 9 is injected into the case 2 will be described with reference to FIGS. 2 (a) and 2 (b). In this embodiment, a thermosetting epoxy resin is used as the mold resin 9. Here, FIG. 2 (a) is a perspective view showing a state after injecting the mold resin 9 into the case 2 in the case mold type capacitor 1 of the present invention, and FIG. 2 (b) is a perspective view of FIG. 2 (a). 2 is a cross-sectional view of a plane portion indicated by a dotted line A in FIG.

  Injection of the mold resin 9 into the case 2 is performed from an opening above the case 2 and the mold resin 9 is filled up to the positions of the through holes 8a and the through holes 8b. To be precise, as shown in FIG. 2B, the through holes 8a and 8b are adjusted so that the upper ends of the through holes 8a are slightly above the upper end of the casting surface of the mold resin 9, and the through holes 8a, A portion excluding the vicinity of the upper end portion of the through hole 8 b is in a state embedded in the mold resin 9. That is, the case mold type capacitor 1 of the present embodiment has a configuration in which a part of the through hole 8 a and the through hole 8 b are embedded in the mold resin 9. Further, the mold resin 9 present in the gap 6a and the gap 6b and the mold resin 9 located on the capacitor element 3 side are connected via the through hole 8a and the through hole 8b. Note that the ends of the bus bar 5a and the bus bar 5b that are connected to the external terminals are exposed from the mold resin 9.

  Then, by heating and curing the mold resin 9, the capacitor element 3 is covered with the mold resin 9, and the capacitor element 3 is protected from the entry of moisture from the outside and thermal shock.

  Next, the effect of the case mold type capacitor 1 of the present embodiment will be described.

  First, the case mold type capacitor 1 of this embodiment can suppress the rise of the mold resin 9 by the above-described configuration, and has high reliability.

  That is, the mold resin 9 located in the gap 6a and the gap 6b and the mold resin 9 located on the capacitor element 3 side are connected by the through-hole 8a and the through-hole 8b provided in the bus bar 5a and the bus bar 5b. The surface tension of the mold resin 9 existing in the gap 6a and the gap 6b is dispersed, and the occurrence of capillary action can be suppressed. As a result, the creeping of the mold resin 9 can be suppressed, and the mold resin 9 can be prevented from adhering to the connection portion between the bus bar 5a and the external terminal of the bus bar 5b, thereby improving the reliability of the case mold type capacitor 1. be able to. Actually, with respect to the case mold type capacitor 1 of the present embodiment, when the presence or absence of creeping of the mold resin 9 was confirmed by appearance inspection, there was no evidence of the mold resin 9 creeping up on the bus bars 5a and 5b. It was.

  However, the upper ends of the through hole 8a and the through hole 8b must be above the casting surface of the mold resin 9, and at least a part of the through hole 8a and the through hole 8b must be exposed from the mold resin 9. . If the through hole 8a and the through hole 8b are completely buried in the mold resin 9, the surface tension becomes difficult to be dispersed, and the effect of the configuration of the present embodiment cannot be fully exhibited.

  By the way, in the case mold type capacitor for vehicles, it is desired to reduce the height because of the problem of the arrangement space. However, in the case mold type capacitor 1 of this embodiment, in order to reduce the height, the external terminals of the bus bar 5a and the bus bar 5b. The connecting portion is not extended vertically above the case 2 but along the outer wall of the case 2. However, when the bus bar 5a and the bus bar 5b are arranged along the outer wall as described above, there is a slight gap between the bus bar 5a and the bus bar 5b and the outer wall. As a result, the capillary phenomenon is more likely to occur, and the mold resin 9 is likely to creep up. Therefore, the above-described configuration in which the through holes 8a and 8b are provided in the bus bar 5a and the bus bar 5b is particularly useful for the case mold type capacitor having the bus bar 5a and the bus bar 5b along the outer wall as in the present embodiment. In addition, the case mold type capacitor 1 of the present embodiment has an excellent configuration that is highly reliable and also has a low profile.

  Further, in order to improve the weather resistance of the case mold type capacitor 1, it is desirable to fill the mold resin 9 without leaving every corner of the housing portion of the case 2, but generally the mold resin 9 is filled to every corner of the housing portion. In order to spread, it is desirable to use a resin having a relatively low viscosity as the mold resin 9. On the other hand, capillary action is more likely to occur with a lower viscosity liquid. That is, in the case mold type capacitor 1 of the present embodiment, since the capillary phenomenon can be suppressed, even a resin having a relatively low viscosity can be used as the mold resin 9, and the housing portion of the case 2 can be used. The mold resin 9 can be filled to every corner. Thus, in the case mold type capacitor 1 of the present embodiment, the housing portion of the case 2 can be sufficiently filled with the mold resin 9, and the weather resistance can be further improved.

  The through holes 8a and the through holes 8b are preferably circular in shape. This is because if the through hole 8a and the through hole 8b are circular, there is no waste in the current path from the capacitor element 3 to the external terminal, and current flows easily. In addition, when the through hole 8a and the through hole 8b are circular as in the present embodiment when subjected to vibration from the outside in actual use, it is possible to suppress local stress concentration in the bus bar 5a and the bus bar 5b. . Therefore, the vibration resistance of the bus bar 5a and the bus bar 5b is also relatively good.

  Further, by providing a plurality of through holes 8a and through holes 8b, it is possible to more effectively suppress the mold resin 9 from creeping up.

  Further, it is desirable that the through hole 8a and the through hole 8b are disposed between adjacent capacitor elements 3. This is because the through-hole 8a and the through-hole 8b are arranged between the capacitor elements 3 so that the through-hole 8a and the through-hole 8b do not obstruct the current path from the capacitor element 3 to the external terminal, and the inductance component is reduced. This is because it can be lowered.

  As a material for the bus bar 5a and the bus bar 5b, any material may be used as long as it has conductivity. However, it is preferable to use copper. This is because copper is excellent in flexibility as well as conductivity, and is easy to process when the through holes 8a and 8b are formed.

  Further, in the case mold type capacitor of the present embodiment, as shown in FIG. 2A, the bus bar 5a and the bus bar 5b partially cover the interface between the mold resin 9 and the case 2. As described above, the bus bar 5a and the bus bar 5b cover the interface between the mold resin 9 and the case 2 so that the intrusion of moisture from the interface between the mold resin 9 and the case 2 into the case mold type capacitor 1 can be suppressed. That is, the configuration (shape) of the bus bar 5a and the bus bar 5b of the present embodiment achieves a low profile and contributes to reducing the possibility of moisture intrusion from the outside of the case mold type capacitor 1.

  As described above, the case mold type capacitor 1 according to the present invention can exhibit excellent reliability, and at the same time, according to the present invention, effects such as a reduction in height can be achieved.

  In addition, this invention is not limited to said Example, It is possible to implement in various changes within the scope of the invention. For example, in the above-described embodiment, a wound metallized film capacitor is used as the capacitor element 3, but the present invention is not limited to this, and a laminated metallized film capacitor may be used as the capacitor element 3. It is possible to obtain the effects of the present invention.

  The case mold type capacitor according to the present invention has excellent reliability and can be suitably used as a capacitor used in various electronic devices, electrical devices, industrial devices, automobiles, etc., and particularly for automobiles requiring high weather resistance Useful in the field.

DESCRIPTION OF SYMBOLS 1 Case mold type capacitor 2 Case 3 Capacitor element 4a, 4b End surface electrode 5a, 5b Bus bar 6a, 6b Gap 7a, 7b Screw hole 8a, 8b Through-hole 9 Mold resin

Claims (3)

A case having an opening on the upper surface;
A capacitor element housed inside the case and having a pair of end face electrodes at both ends; and
Mold resin that is injected into the case and molds the capacitor element;
One end is connected to each of the pair of end surface electrodes of the capacitor element, and the other end is exposed from the mold resin and includes a pair of bus bars respectively connected to external terminals,
The bus bar while being disposed along the inner wall of the case, have a through hole part is embedded in the molding resin,
A plurality of the capacitor elements are accommodated inside the case so that the pair of end face electrodes respectively face the inner side walls of the case,
The bus bar electrically connects the end face electrodes of the adjacent capacitor elements,
The through hole is a case mold type capacitor provided between connecting portions where each of the adjacent capacitor elements is connected to the bus bar . The capacitor element has a flat shape,
The case mold type capacitor according to claim 1, wherein the through hole is provided between the curved portions of the adjacent flat capacitor elements. The through hole is case-molded capacitor according to claim 1 or 2 provided a plurality.

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