JP3975993B2 - Case mold type film capacitor - Google Patents

Description

  The present invention relates to a case mold type film capacitor that includes a capacitor element in an outer case and is resin-molded in the outer case.

  In recent years, case mold type film capacitors have been developed in various fields such as the conventional home appliance field, the industrial field, and the vehicle field. Among them, a case mold type film capacitor for a vehicle is required to have a small size in addition to performance and high reliability capable of withstanding a high voltage and a high current.

  However, since the capacity is proportional to the amount of film used as a dielectric, the amount of film used increases as the demand for larger capacity increases, resulting in an increase in volume. Therefore, in order to compensate for this and realize miniaturization, it is necessary to reduce the thickness of the case containing the capacitor element and the thickness of the filling resin covering the element. However, when these thicknesses are reduced, if the entire volume is large, there is a concern that cracks or cracks may occur in the outer case or the filled resin due to the effect of thermal shock. Further, since the moisture resistance is deteriorated by reducing the thickness, it is difficult to ensure reliability by reducing each thickness.

  In addition, in order to reduce thermal shock, it is conceivable to use a soft rubber resin as the resin that fills the case containing the capacitor element. Because of the proportional relationship, the use of such a resin will impair the moisture resistance.

  In this way, in case mold type film capacitors that are used under severe usage conditions, especially for vehicles, and have strict requirements, performance that contradicts the increase in capacity, high thermal shock, high humidity resistance, and downsizing. Satisfying these simultaneously is a major issue.

  As a means for solving such a problem, a conventional case mold type film capacitor is known in which a soft resin is filled in the vicinity of the opening surface and a hard resin is filled in the periphery of the element (see, for example, Patent Document 1).

FIGS. 6A and 6B show the metalized film capacitor in the above conventional example, where FIG. 6A is a front view showing a cross section, and FIG. 6B is a side view thereof. In FIG. 6 , 101 is an exterior case, 102 is a capacitor element, 103 is an electrode portion, 104 is a bus bar, 108 is a hard filling resin, 109 is solder, and 110 is a soft filling resin.

  About the metallized film capacitor comprised as mentioned above, the structure is demonstrated.

  The capacitor element 102 is formed by winding a metallized film, and electrode portions 103 are provided at both end portions in the film width direction. Furthermore, the electrode part 103 and the bus bar 104 are connected by the solder 109, and the end part of the bus bar 104 goes out of the outer case 101 and is connected to the outside.

  The outer case 101 has an opening at the top in FIG. 6 and includes a plurality of capacitor elements 102 arranged side by side. Around the capacitor element 102, a hard filling resin 108 is filled up to a height of 5 mm from the upper end surface of the capacitor element 102 to protect and hold the element 102. In addition, the material has selected the epoxy resin excellent in insulation, moisture resistance, mechanical strength, and adhesiveness.

Furthermore, the soft filling resin 110 is filled in the surface of the exterior case 101 opening above the hard filling resin 108. The soft filling resin 110 has a thickness of 2 mm, relieves stress due to thermal shock, prevents cracking and cracking of the soft filling resin 110 itself, and uses silicon.
JP 59-11615 (FIG. 1)

  However, the conventional case mold type film capacitor has a problem that the filling resin has a two-layer structure, is complicated, and hinders downsizing.

  An object of the present invention is to provide a case mold type film capacitor that has a simple structure, is easy to manufacture, and realizes miniaturization.

In order to solve the above problems, a case mold type film capacitor according to the present invention includes a capacitor element in which a metallized film is wound or laminated, a flat plate covering the entire capacitor element and having a through hole, the capacitor element, and the capacitor element. A case mold type film capacitor comprising an exterior case having a flat plate and having an opening, and a filling resin filling the inside of the case, wherein the flat plate is a plywood of resin and copper foil, and at least the exterior It is arranged on the opening side of the case, and the filling resin on both sides sandwiching the flat plate is connected through the through hole.

  As described above, the case mold type film capacitor of the present invention has a high reliability and a simple structure at the same time by arranging a flat plate or bus bar which covers the entire capacitor element and has a through hole on the case opening surface. Can be realized. In addition, soldering is facilitated by providing protrusions in the through holes.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.

(Embodiment 1)
First, Embodiment 1 of the present invention will be described with reference to FIG. 1A and 1B are diagrams showing a case mold type film capacitor according to Embodiment 1 of the present invention. FIG. 1A is a plan view, FIG. 1B is a front view, and FIG. 1C is a side view.

  In FIG. 1, reference numeral 1 denotes an exterior case having an opening, which is made of a resin having a thickness of 2 mm. Reference numeral 2 denotes a capacitor element, which is formed by winding or laminating a metallized film having a thickness of several μm and a width of several centimeters. Electrode portions 3 are formed on both ends of the element by a method such as spraying a metal such as zinc. ing. In addition, as for this electrode part 3, the sprayed layer is a pile of particle | grains, and is planar by the thickness of about 1 mm. Reference numeral 4 denotes a flat-plate bus bar having a thickness of 1.2 mm, and is made of electrolytic copper. The portion of the bus bar 4 that is pulled out of the case is a terminal portion having a width of about 20 mm, a thickness of 2 mm, and a φ8 mm hole. Reference numeral 5 denotes a flat plate of a size that covers the entire capacitor element 2, and is a plywood made of resin and copper foil having several through holes 5a. Further, 8 is a filling resin, which is a thermosetting epoxy resin.

  The case mold type film capacitor configured as described above will be described in more detail.

  The outer case 1 protects and holds the components constituting the capacitor, and improves insulation and moisture resistance from the inside. Next, the capacitor element 2 that is a dielectric has a power storage function, and is connected to the outside from the capacitor element 2 via the electrode portion 3 that is a conductor and the bus bar 4 connected thereto. Further, the flat plate 5 is for suppressing moisture ingress from the outside and improving moisture resistance, and the through-hole 5a provided in the flat plate 5 is filled with a filling resin 8 inside, so that the vicinity of the opening surface of the outer case 1 is obtained. It functions to connect the filling resin 8 and the lower filling resin 8 on the opposite side across the flat plate 5 to improve the strength of the filling resin 8 near the opening surface. Further, since the flat plate 5 is arranged so that the capacitor element 2 is entirely covered with the opening surface of the outer case 1, moisture intrusion can be suppressed. The overall size can be reduced.

  As described above, according to the present embodiment, by arranging the flat plate 5 provided with the through hole 5a on the entire upper surface of the element 2, the filling resin strength in the vicinity of the opening surface of the outer case 1 is increased, and thermal shock resistance and moisture resistance are increased. Both achieve an excellent case mold type film capacitor with a simple filled resin single layer structure.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. 2A and 2B are diagrams showing a case mold type film capacitor according to Embodiment 2 of the present invention. FIG. 2A is a plan view, FIG. 2B is a front view, and FIG. 2C is a side view.

  In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the present embodiment, the difference from the first embodiment is that the entire capacitor element is covered with a bus bar 4 instead of the flat plate 5, and as shown in FIG. It has the flat plate part 4b of the magnitude | size which covers all the electrode parts 3 of the element 2 one side.

  Further, the flat plate portion 4b of the bus bar 4 is provided with a through hole 4a as in the flat plate 5 in the first embodiment.

  In the present embodiment, as described in the first embodiment, the filling resin 8 in the vicinity of the opening surface of the outer case 1 passes through the opposite filling resin 8 with the flat plate portion 4b of the bus bar 4 interposed therebetween. Since the holes are connected through the holes 4a, the strength of the filling resin 8 in the vicinity of the opening surface can be increased.

  Here, since the moisture resistance test for showing the difference in moisture resistance between the case where the bus bar covers the entire upper surface of the element and the case where the bus bar does not cover is performed, the result is shown in FIG. FIG. 3 is a graph showing the results of measuring the rate of change in capacitance after being left for a long time, with the horizontal axis representing the standing time and the vertical axis representing the rate of change in capacitance from the initial capacitance. Show. Further, as an example according to the present embodiment, a prototype in which a capacitor element is covered with a bus bar is referred to as Example 1, and a prototype in which the element is not covered with a bus bar is referred to as Comparative Example 1. Note that the distance from the upper part of the capacitor element to the filling resin surface is the same in both Example 1 and Comparative Example 1. In Example 1, the distance from the upper end of the bus bar to the filling resin surface is 2 mm.

  As is clear from FIG. 3, the capacity reduction rate at the same time is lower in Example 1 in which the bus bar covers the entire upper surface of the element than in Comparative Example 1 in which the bus bar does not cover. This indicates that when the entire upper surface of the element is covered with a bus bar, moisture can be prevented from entering, and moisture resistance is better.

As described above, according to the present embodiment, by arranging the flat plate portion 4b of the bus bar 4 provided with the through hole 4a over the entire surface covering the capacitor element 2, the filling resin strength in the vicinity of the opening surface of the outer case 1 is increased. In addition, a case mold type film capacitor having a simple single-layer resin-filled structure that is excellent in both thermal shock resistance and moisture resistance and that can shorten the process can be realized.

(Embodiment 3)
Next, Embodiment 3 of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4A and 4B are diagrams showing a case mold type film capacitor according to Embodiment 3 of the present invention, in which FIG. 4A is a plan view, FIG. 4B is a front view, and FIG. 4C is a side view. 5 shows an enlarged view of the through hole 4a portion of the bus bar 4. As shown in FIG.

  In the present embodiment, the same parts as those in the second embodiment are denoted by the same reference numerals and the detailed description thereof is omitted.

In the present embodiment, the difference from the second embodiment is that, as shown in FIG. 4, the capacitor element 2 is arranged so that the electrode portions 3 provided on both end faces of the capacitor element 2 are parallel to the opening surface of the outer case 1. the arranged in the outer casing 1, in that a protruding portion 6 in the through hole 4a is further provided in the flat plate portion 4b of the bus bar 4. Only this difference will be described.

In the present embodiment, the flat plate portion 4b of the bus bar 4 is provided with a through-hole 4a of 12mm square at regular intervals, as shown in FIG. 5, to facilitate the soldering operation for connecting the electrode portion 3 Therefore, a protrusion 6 having a width of 1 mm and a length of 2 mm is provided inside the through hole 4a. 9 is solder which solders between the electrode part 3 of the capacitor | condenser element 2 and the projection part 6 of the bus-bar 4. FIG. Further, the filling resin 8 is molded up to about 1 to 2 mm from the upper surface of the bus bar 4.

  The filling resin 8 near the opening surface of the outer case 1 and the lower element electrode portion 3 are connected through the through hole 4a, and the strength of the filling resin 8 near the opening surface is increased. This is because the column of the capacitor element 2 is connected to the filling resin 8 on the surface of the exterior case opening because the adhesive strength between the filling resin 8 and the electrode portion 3 is very strong. Therefore, even the thickness of the filling resin 8 on the surface of the opening of only 1 or 2 mm has sufficient thermal shock resistance.

In this regard, as shown in FIG. 2 of the second embodiment, a prototype in which the capacitor element 2 is arranged so that the electrode portion 3 faces the side surface of the outer case 1, and as shown in FIG. 4 of the present embodiment. A prototype in which the capacitor element 2 is arranged so that the electrode portion 3 faces the opening surface of the outer case 1 was prepared, and a thermal shock test at −40 ° C. to 90 ° C. was performed. The results are shown in Table 1. .

  In Table 1, Examples 1, 2, and 3 are prototypes based on the capacitor element array shown in FIG. 2 of Embodiment 2, and the thickness of the filling resin 8 from the upper surface of the bus bar 4 is 2 mm, 3 mm, and 5 mm, respectively. Is. In addition, Example 1 is a thing of the same specification as Example 1 in the graph which shows the moisture-proof electricity test result of FIG. Example 4 is a prototype using the capacitor element arrangement shown in FIG. 4 of the present embodiment, and the thickness of the filling resin 8 from the upper surface of the bus bar 4 is 1 mm.

As shown in Table 1, in Examples 1 to 3, which are examples of the capacitor element arrangement according to the second embodiment, the resin thickness above the upper surface of the bus bar 4 must be filled about 5 mm or more as in Example 3. It can be seen that the thermal shock resistance is not the same level as in Example 4 which is an example of the present embodiment.

  Moreover, about Example 4, also about moisture resistance, it is as good as Example 1 as shown by the graph which shows the moisture-proof electricity test result of FIG.

  Thus, as is clear from FIG. 3 and Table 1, in Example 4 according to the present embodiment, the thermal shock resistance and the humidity resistance are good.

  As described above, according to the present embodiment, the strength of the filling resin in the vicinity of the opening surface of the outer case 1 is increased, and a case-molded film capacitor having a simple filling resin single-layer structure having excellent thermal shock resistance and moisture resistance is realized. At the same time, the filling resin thickness can be reduced.

  In Embodiments 1 to 3, the bus bar is made of electrolytic copper, but the same effect can be obtained if the bus bar is made of metal. Moreover, although the element electrode part is made of zinc, an alloy of zinc and other metals may be used.

  The metallized film capacitor of the present invention can be applied to an inverter circuit for driving a large capacity motor such as a hybrid vehicle and an electric vehicle, and can be widely used for other consumer and industrial electric devices.

(A) Plan view showing the case mold type film capacitor in Embodiment 1 of the present invention (b) Front view (c) Side view (A) The top view which shows the case mold type film capacitor in Embodiment 2 of this invention (b) The front view (c) The side view Graph showing the results of moisture resistance test (A) The top view which shows the case mold type film capacitor in Embodiment 3 of this invention (b) The front view (c) The side view The figure which expanded the through-hole 4a part of the bus-bar 4 (A) Front view showing a conventional case mold type film capacitor (b) Side view showing a conventional case mold type film capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exterior case 2 Capacitor element 3 Electrode part 4 Bus bar 4a Through-hole 4b Flat plate part 5 Flat plate 5a Through hole 6 Projection part 8 Filling resin

Claims (2)

Capacitor element wound or laminated with metallized film, flat plate covering the entire capacitor element, having a through hole, external case containing the capacitor element and the flat plate and having an opening, and filling the case A case mold type film capacitor having a filling resin to be used, wherein the flat plate is a plywood of resin and copper foil, and is disposed at least on the opening side of the exterior case, and the filled resin on both sides sandwiching the flat plate is A case mold type film capacitor connected through the through hole. The case mold type film capacitor according to claim 1, wherein a plurality of the through holes are provided.

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