JP2013211324A - Case molded capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a case molded capacitor used on hybrid automobiles or the like with an enhanced reliability.SOLUTION: The case molded capacitor has bus bars 2 and 3 which are constituted including: an electrode connection part 2a connected to an electrode; an external connection terminal 2b connected to the external; and a link portion 2c linking the electrode connection part 2a and the external connection terminal 2b. A part of the link portion of at least one bus bar 2(3) is a formed in a comb-teeth portion 2 g (3 g) in contact with a molding resin, and in which neighboring comb-teeth are arranged not to overlap with each other in a side view. This constitution prevents a local stress from occurring in the molding resin even when the molding resin is subjected to a thermal shock; to thereby prevent the molding resin from clacking due to a thermal shock. As a result, the reliability of the case molded capacitor is enhanced.

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 smoothing, filtering, and snubbing of a motor drive inverter circuit 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 an electric motor for HEV has a high operating voltage range of several hundred volts, a metallized film capacitor having high withstand voltage and low loss electric characteristics has attracted attention as a capacitor used in connection with such an electric motor. In addition, the trend of adopting metalized film capacitors with a very long life is also conspicuous due to the demand for maintenance-free in the market.

  And, metallized film capacitors used for HEVs are strongly required to have external environmental performance such as moisture resistance and heat resistance for reasons such as their installation location, and therefore, generally a plurality of metallizations connected in parallel by bus bars. A film capacitor is housed in a resin case, and a mold resin is cast into the resin case. By casting the mold resin in this manner, the metalized film capacitor is protected from the intrusion of moisture from the outside and the influence of heat.

  A conventional configuration of a case mold type capacitor containing such a metallized film capacitor will be described by taking the case mold type capacitor described in Patent Document 1 as an example. FIG. 3 is a perspective view showing the configuration of the case mold type capacitor described in Patent Document 1. As shown in FIG.

  As shown in FIG. 3, the conventional case mold type capacitor has a bus bar 102 and a bus bar 103 made of a copper plate or the like connected to both end faces of the metallized film capacitor element 101. 103 is housed inside the case 104. The case 104 is filled with a mold resin (not shown) up to a resin surface 105 indicated by a dotted line as shown in FIG. 3 to protect the metallized film capacitor element 101.

  Generally, a case mold type capacitor is configured as described above.

  By the way, since the bus bar 102 and the bus bar 103 are made of metal and have a different thermal expansion coefficient from the surrounding mold resin, the thermal expansion of the bus bar 102, the bus bar 103 and the mold resin when subjected to a large thermal shock during actual use. Due to the difference, thermal stress may be applied around the interface between the bus bar 102 and the bus bar 103 and the mold resin. If the mold resin cannot withstand this thermal stress, cracks may occur in the mold resin.

  As described above, when a crack occurs in the mold resin, the crack may become a moisture intrusion route from the outside, that is, it may lead to a decrease in moisture resistance of the case mold type capacitor.

  With respect to such a problem, a technique described in Patent Document 1 proposes a technique in which a part of the bus bar 102 and the bus bar 103 are continuously covered with the insulating paper 106 from the inside of the mold resin to the outside of the mold resin.

  That is, in the technique described in Patent Document 1, the thermal expansion difference between the bus bar 102, the bus bar 103, and the mold resin is absorbed by covering the bus bar 102, the bus bar 103 with the insulating paper 106 having a relatively close thermal expansion coefficient to the mold resin. The generation of cracks was suppressed.

JP 2008-288242 A

  Certainly, according to the technique described in Patent Document 1, the occurrence of cracks in the mold resin can be suppressed, and the moisture resistance of the case mold type capacitor can be improved.

  However, in the technique described in Patent Document 1, since a new component member called the insulating paper 106 is added, the cost for the insulating paper 106 is increased, and the labor for arranging the insulating paper 106 at a predetermined position in the manufacturing process is increased. There was a problem of increase.

  Moreover, the problem of preventing cracks in the mold resin due to thermal shock is an extremely important issue in the field of HEV capacitors used in various external environments such as cold regions and high-temperature and high-humidity regions, and we will continue to take solutions. This can greatly contribute to the development of HEV capacitors.

  Accordingly, an object of the present invention is to provide a case mold type capacitor that has excellent moisture resistance by suppressing generation of cracks in the mold resin due to thermal shock without increasing the number of components of the case mold type capacitor.

  In order to solve the above problems, a case mold type capacitor of the present invention includes an electrode connection portion connected to an electrode of a metallized film capacitor element, an external connection terminal portion connected to the outside, the electrode connection portion and the external A pair of bus bars configured to connect to the connection terminal portion, and of the pair of bus bars, at least one of the connection portions of the bus bars is in contact with the mold resin and adjacent to the comb. It has the structure formed in the comb-tooth shape formed in the comb-tooth shape arrange | positioned so that teeth may not mutually overlap in side view.

  In general, the wider the bus bar embedded in the mold resin, the larger the volume, the greater the local thermal stress generated when subjected to thermal shock, and the easier it is for the mold resin to crack. I know.

  On the other hand, in the case mold type capacitor of the present invention, the shape of the bus bar is a comb-teeth shape in which comb teeth are alternately arranged at the front and back.

  That is, the width of the entire comb teeth is the same as that of the bus bar of the conventional case mold type capacitor, but the volume per comb tooth is small, and these comb teeth are arranged apart from each other. As a result, it is possible to prevent a large thermal stress from being generated locally, and to suppress occurrence of cracks in the mold resin due to thermal shock.

  Therefore, according to the present invention, a case mold type capacitor having excellent moisture resistance can be provided.

The perspective view which shows the structure of the metallized film capacitor | condenser element of the case mold type capacitor | condenser of this invention, and a bus-bar The perspective view which shows the structure of the case mold type capacitor | condenser of this invention Perspective view of a conventional case mold type capacitor

  Hereinafter, the configuration of the case mold type capacitor according to the present embodiment will be described with reference to FIGS.

  FIG. 1 is a perspective view showing a configuration of a metallized film capacitor element and a bus bar according to the present embodiment, and FIG. 2 is a perspective view showing a configuration of a case mold type capacitor according to the present embodiment.

  The metallized film capacitor element 1 used in the present embodiment has a pair of metallized films in which a metal vapor-deposited electrode is formed on one or both sides of a dielectric film made of polypropylene film or the like, and the metal vapor-deposited electrode is a dielectric film. And wound in a state of facing each other. Further, this metallized film capacitor element 1 is provided with metallicon electrodes sprayed with zinc on both end faces, and this metallicon electrode is a pair of extraction electrodes of a P electrode 1a and an N electrode 1b. In FIG. 1, the front side is the P pole 1a and the back side is the N pole 1b.

  As shown in FIG. 1, in the case mold type capacitor of the present embodiment, three metallized film capacitor elements 1 are used. However, the number is not limited to this, and other numbers may be used.

  A P-pole bus bar 2 and an N-pole bus bar 3 are connected to a pair of extraction electrodes of the P pole 1a and the N pole 1b of the metallized film capacitor element 1, respectively. In the present embodiment, three metallized film capacitor elements 1 are connected and electrically connected in parallel by the P-pole bus bar 2 and the N-pole bus bar 3.

  First, the P pole bus bar 2 will be described.

  The P-pole bus bar 2 includes an electrode connection portion 2a provided at one end, an external connection terminal portion 2b provided at the other end, and a connection portion 2c that connects them. These electrode connection portion 2a, external connection terminal portion 2b, and connection portion 2c are integrally formed using a single copper plate, as shown in FIG.

  The electrode connecting portion 2 a is a portion that is directly connected to the P pole 1 a of the metallized film capacitor element 1. The electrode connection portion 2a has a rectangular flat plate shape, and is arranged so that the longitudinal direction of the flat plate straddles the end faces of the three metallized film capacitor elements 1. The electrode connecting portion 2a has a plurality of tongue-like solder welds 2d on the long side portion of the flat plate, and the metal welded film capacitor element is obtained by soldering the solder welds 2d to the P pole 1a. 1 and the P pole bus bar 2 are electrically connected.

  The external connection terminal portion 2b is a portion connected to a terminal (not shown) of an external device. The external connection terminal portion 2b has a tongue-like shape and is provided with a hole in the center. In the case mold type capacitor of the present embodiment, a bolt (not shown) is inserted into this hole and fastened to a terminal of the external device to electrically connect the terminal of the external device and the P-pole bus bar 2. Yes.

  The connecting portion 2c is formed integrally with the electrode connecting portion 2a and the external connecting terminal portion 2b, and connects the electrode connecting portion 2a and the external connecting terminal portion 2b.

  As shown in FIG. 1, the connecting portion 2c extending in a flat plate shape from the long side of the electrode connecting portion 2a is perpendicular to the upper side in FIG. 1 (in the direction away from the metallized film capacitor element 1) in the vicinity of the N pole 1b. The first bent portion 2e is bent. Further, the connecting portion 2c has a second bent portion 2f bent above the first bent portion 2e in parallel with the extending direction, and the external connection terminal portion 2b is connected to the second bent portion 2f. It is extended.

  The connecting portion 2c includes a comb tooth portion 2g formed in a comb shape between the first bent portion 2e and the second bent portion 2f. The comb teeth constituting the comb tooth portion 2g are each flat and the P-pole bus bar 2 has five comb teeth.

  In these comb teeth, adjacent comb teeth are alternately arranged in front and back (staggered arrangement). In the present embodiment, three comb teeth are arranged in the first tooth row close to the P pole 1a, and two comb teeth are arranged in the second tooth row close to the N pole 1b, and these first teeth are arranged. The row and the second tooth row are spaced apart.

  That is, if the line of sight (arrow A in FIG. 1) perpendicular to the extending direction of the connecting portion 2c and parallel to the surface of the flat plate portion of the connecting portion 2c is “side view”, adjacent comb teeth Are arranged so as not to overlap each other.

  As is apparent from FIG. 1, the comb tooth portion 2g is formed by dividing the flat plate portion of the connecting portion 2c into five comb teeth and arranging the divided comb teeth on the front and rear sides. The width of the entire tooth is equal to the width of the flat plate portion of the connecting portion 2c. That is, the sum of the cross-sectional areas of these five comb teeth is equal to the cross-sectional area of the flat plate portion of the connecting portion 2c. In addition, the cross-sectional area described here is a cross-sectional area in a plane perpendicular to the comb-tooth portion 2g, and a cross-sectional area in a plane perpendicular to the extending direction of the flat plate portion of the connecting portion 2c.

  Next, the N pole bus bar 3 will be described.

  The N pole bus bar 3 has basically the same configuration as the P pole bus bar.

  In other words, the N pole bus bar 3 is also connected to the N pole 1b by solder welding, the electrode connection portion 3a, the external connection terminal portion 3b connected to a terminal of an external device with a bolt, and the like. It is comprised by the connection part 3c which connects the connection terminal part 3b.

  As shown in FIG. 1, the connecting portion 3c of the N-pole bus bar 3 does not have a flat plate portion like the P-pole bus bar 2, and the whole is a comb-teeth-like comb tooth portion 3g. The configuration of this comb tooth is the same as that of the comb tooth portion 2g of the P-pole bus bar 2, but the N-pole bus bar 3 has two comb teeth in the tooth row closer to the N pole 1b and is far from the N pole 1b. Three comb teeth are arranged in the side tooth row, and these tooth rows are spaced apart. That is, the number of comb teeth constituting the front and rear tooth rows is different from that of the P-pole bus bar 2.

  The area obtained by adding the cross-sectional areas of these five comb teeth is equal to the cross-sectional area of the external connection terminal portion 3b. In the present embodiment, the P-pole bus bar 2 and the N-pole bus bar 3 each have five comb teeth, but other numbers may be used.

  As shown in FIG. 2, the metallized film capacitor element 1, the P-pole bus bar 2 and the N-pole bus bar 3 thus configured are accommodated in a resin case 4 and are resin-molded.

  The resin case 4 has a rectangular parallelepiped shape with an open upper surface, and is formed of polyphenylene sulfide.

  The metallized film capacitor element 1 to which the P pole bus bar 2 and the N pole bus bar 3 are connected is accommodated in the resin case 4 with the direction in which the P pole bus bar 2 and the N pole bus bar 3 are not connected as a downward direction in FIG. The external connection terminal portion 2 b and the external connection terminal portion 3 b are in a state of protruding outward from the opening of the resin case 4.

  Further, the resin case 4 is filled with an insulating mold resin 5 made of an epoxy resin. This mold resin 5 protects the metallized film capacitor element 1 from moisture and heat from the outside.

  The mold resin 5 covers the plurality of metallized film capacitor elements 1 accommodated in the resin case 4, the P-pole bus bar 2 and the N-pole bus bar 3 connecting the plurality of metallized film capacitor elements 1. Although the resin case 4 is filled, the external connection terminal portion 2b and the external connection terminal portion 3b are in a state of being exposed from the mold resin 5 because they are connected to the terminals of the external device.

  As shown in FIG. 2, the mold resin 5 is filled and solidified so that the resin surface is positioned at the same height as the comb teeth 2 g and the comb teeth 3 g of the P pole bus bar 2 and the N pole bus bar 3. That is, the comb tooth portion 2g and the comb tooth portion 3g are arranged from the inside of the mold resin 5 to the outside of the mold resin 5.

  In FIG. 2, the case mold type capacitor of the present embodiment is illustrated so that the opening of the resin case 4 is upward. However, the opening is not limited to this in actual use, for example, the opening is in the vertical direction. You may use it in the state that turned down.

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

  In the case mold type capacitor according to the present embodiment, a part of the P pole bus bar 2 and the N pole bus bar 3 are arranged so that adjacent comb teeth do not overlap each other in side view, The comb teeth 2g and the comb teeth 3g are arranged in contact with the mold resin.

  In the conventional bus bar configuration, a large thermal stress is locally applied to the mold resin due to a difference in thermal expansion between the bus bar and the mold resin, and cracks may occur.

  On the other hand, in the case mold type capacitor of the present embodiment, a part of the P-pole bus bar 2 and the N-pole bus bar 3 is comb-like and these comb teeth are arranged apart from each other. Even if the pole bus bar 3 receives a thermal shock, the volume expansion amount per comb tooth is small, and the mold resin 5 does not receive a large thermal stress locally.

  As a result, generation of cracks in the mold resin 5 due to thermal shock can be suppressed, and the case mold type capacitor of the present embodiment has excellent characteristics regarding moisture resistance.

  As described above, the cross-sectional areas of the comb-tooth portion 2g and the comb-tooth portion 3g are equal to the cross-sectional area of the flat plate portion of the connecting portion 2c and the external connection terminal portion 3b. The current density does not change, and the current density is equivalent to that of a bus bar having a conventional configuration. Therefore, the comb tooth portion 2g and the comb tooth portion 3g do not generate heat locally.

  Moreover, it is preferable that these comb-tooth part 2g and the comb-tooth part 3g are arrange | positioned at the height of the mold resin 5 surface. That is, the comb tooth portion 2g and the comb tooth portion 3g are arranged from the inside of the mold resin 5 to the outside of the mold resin 5.

  This is because the surface of the mold resin 5 is most easily cracked when subjected to thermal shock. If cracks are generated on the surface of the mold resin 5 in this way, it is easy for water to enter the mold resin 5 from the outside, which is not preferable. Therefore, it is most suitable to arrange the comb tooth portion 2g and the comb tooth portion 3g at a location corresponding to the surface of the mold resin 5 from the viewpoint of improving the moisture resistance of the case mold type capacitor.

  The comb tooth portion 2g and the comb tooth portion 3g are each constituted by two rows of teeth arranged in parallel. This is because if the distance between the dentitions can be sufficiently secured, the effect of the present invention can be sufficiently obtained with two dentitions, and it is not necessary to dare to make more than three. . If too many tooth rows are provided, the processing of the bus bar for forming the tooth rows becomes complicated, and the entire case mold type capacitor may become large, which is not preferable. From such a point, in the present embodiment, the comb tooth portion 2g and the comb tooth portion 3g are constituted by two rows of tooth rows.

  In the present embodiment, both ends of the comb tooth portion 2g and the comb tooth portion 3g are bent portions. By setting it as such a design, the process for forming the comb-tooth part 2g and the comb-tooth part 3g becomes easy.

  For example, when forming a comb tooth portion protruding front and rear with respect to the surface of the flat plate, it is necessary to perform bending work by changing the bending direction back and forth for each comb tooth row, which is difficult to process. is there.

  On the other hand, since the bending direction of the bending portion of the comb tooth portion 2g and the comb tooth portion 3g of the present embodiment is the same direction, the comb tooth portion 2g and the comb tooth portion 3g are bent for each tooth row of the comb teeth. The adjacent comb teeth can be separated from each other by simply changing the angle, and can be easily formed.

  Thus, the comb tooth portion 2g and the comb tooth portion 3g according to the present embodiment can be easily processed.

  As described above, the case mold capacitor according to the present invention can suppress the occurrence of cracks in the mold resin due to thermal shock, and has excellent moisture resistance, and thus has high reliability.

  The present invention is not limited to the case mold type capacitor of the above-described embodiment, and can be implemented with various modifications within the scope of the invention.

  The case mold type capacitor according to the present invention can suppress the occurrence of cracks in the mold resin due to thermal shock, and has excellent moisture resistance, and therefore has high reliability. Therefore, it can be suitably used as a capacitor for a hybrid vehicle that is used in various external environments and requires high reliability.

DESCRIPTION OF SYMBOLS 1 Metallized film capacitor | condenser element 1a P pole 1b N pole 2 P pole bus bar 2a Electrode connection part 2b External connection terminal part 2c Connection part 2d Solder welding part 2e 1st bending part 2f 2nd bending part 2g Comb tooth part 3 N Polar bus bar 3a Electrode connection part 3b External connection terminal part 3c Connection part 3g Comb tooth part 4 Resin case 5 Mold resin

Claims (4)

An element provided with a pair of electrodes on both end faces;
A pair of bus bars connected to the electrodes of the element;
A resin case having an opening and containing the element and the bus bar therein;
Filled in the resin case, provided with a mold resin that molds the element and the bus bar except for one end of the bus bar,
The pair of bus bars is
An electrode connection connected to the electrode;
An external connection terminal connected to the outside;
It is composed of a connecting part that connects the electrode connecting part and the external connecting terminal part,
Of the pair of bus bars, at least one part of the connecting portion of the bus bars is in the form of comb teeth that are in contact with the mold resin and arranged so that adjacent comb teeth do not overlap each other in a side view. Case mold type capacitor. 2. The case mold type capacitor according to claim 1, wherein a part of the connecting portion formed in a comb shape is located on a resin surface of the mold resin. 2. The case mold type capacitor according to claim 1, wherein a part of the connecting portion formed in a comb-like shape includes a first tooth row and a second tooth row that are spaced apart from each other. 2. The case mold type capacitor according to claim 1, wherein a part of the connecting portion formed in a comb-teeth has a bent portion at both ends thereof, and a bending direction in each of the bent portions of the comb teeth is the same direction.

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