Film capacitor and method for manufacturing the same

Abstract

To enable the film capacitor to be securely attached to an external mounting surface. [Solution] The film capacitor is equipped with a mounting member 20 for attachment to an external mounting part, and the mounting member is embedded in the molded resin so as to penetrate the molded resin in a predetermined through-direction x. The mounting member has a through-hole extending in the through-direction, with both ends exposed from the molded resin, and a threaded portion with a female thread formed at the rear end of the through-hole. The mounting member is then fixed together with the capacitor unit 1A inside the resin casting jig by screwing in a bolt 45, and the capacitor unit and mounting member are sealed with molded resin by filling with a liquid resin such as epoxy resin.

Description

Technical Field

[0001] The present invention relates to a film capacitor in which a capacitor unit including a capacitor element is sealed with a molding resin, and a method for manufacturing the same.

Background Art

[0002] Conventionally, as a capacitor used for industrial machines, vehicles, etc., there is a resin-molded type case-less film capacitor in which a capacitor unit including a capacitor element is sealed with a molding resin.

[0003] In the case of a case-encased film capacitor, for example, due to the mounting structure to an external mounting portion formed in a metal case, the film capacitor can be mounted to the mounting portion, and such a mounting structure has high mounting strength and can be easily formed in the case. On the other hand, in the case of a case-less film capacitor, it is necessary to process the molding resin itself into a structure that can be attached to an external mounting portion, and since the strength of the molding resin itself is weak, high mounting strength as in the case of a case-encased film capacitor cannot be obtained and reliability is lacking.

[0004] Therefore, conventionally, as described in Patent Document 1, when sealing a capacitor unit with a molding resin, a fastening member such as a nut is insert-molded so that the fastening member is embedded in the molding resin, and a fastening member such as a bolt is screwed into the fastening member (nut) on the molding resin side to attach the film capacitor to an external mounting portion (fixing portion). At this time, one end face of the fastening member is embedded in the molding resin surface in a state of being exposed from the molding resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, as described in Patent Document 1, in the case of a mounting structure in which the fastener to be fastened is embedded in the surface of the molded resin, although the mechanical strength is high when a fastener such as a bolt is screwed into the fastener such as a nut, the contact area between the fastener such as a nut and the molded resin is small, and the adhesive strength between the fastener and the molded resin surrounding the fastener is not necessarily sufficiently high.

[0007] Therefore, when a film capacitor is attached to an external mounting part by screwing together a fastener such as a nut and a fastener such as a bolt, excessive external force may be applied, causing the adhesive strength between the fastener and the surrounding molded resin to partially decrease, resulting in weak points and potentially leading to a decrease in mounting strength.

[0008] This invention has been made in view of the above-mentioned problems, and aims to enable a film capacitor to be firmly attached to an external mounting surface. [Means for solving the problem]

[0009] To achieve the above objective, the film capacitor according to the present invention is a film capacitor in which a capacitor unit including a capacitor element is sealed with a molded resin, and is characterized by having a mounting member for attachment to an external mounting part, wherein the mounting member is embedded in the molded resin so as to penetrate the molded resin in a predetermined penetrating direction, has a through hole extending in the penetrating direction, and both ends of the through hole are exposed from the molded resin.

[0010] With this configuration, since the mounting member is embedded in the molded resin so as to penetrate it, the contact area with the molded resin is larger compared to conventional fasteners embedded on the surface of the molded resin, resulting in stronger adhesion between the mounting member and the surrounding molded resin. For this reason, for example, by inserting a long bolt through the through-hole of the mounting member, the film capacitor can be firmly attached to the external mounting surface via the mounting member.

[0011] In this case, it is preferable to have a threaded portion with a female thread formed at one end of the through hole, and to fix the mounting member to a resin casting jig for filling with molded resin, which is different from the external mounting part, by screwing a bolt into the threaded portion. This allows the mounting member to be accurately positioned relative to the resin casting jig when filling with molded resin, and the mounting member can be embedded in the molded resin without misalignment.

[0012] Furthermore, it is preferable that the inner diameter of the threaded portion is larger than the inner diameter of the through hole. With this configuration, when inserting, for example, a long bolt into the through hole of the mounting member in order to attach the film capacitor to an external mounting part, the threaded portion will not interfere with the long bolt, and the mounting work can be carried out smoothly.

[0013] Furthermore, it is preferable that the other end of the through hole in the mounting member has a fitting portion for a positioning jig used to position the mounting member relative to a resin casting jig for filling with mold resin. With this configuration, when one end of the mounting member is fixed to the resin casting jig, the positioning jig can be fitted into the fitting portion at the other end, thereby allowing the mounting member to be held vertically relative to the resin casting jig and fixed in a more precisely positioned state.

[0014] Furthermore, the outer surface of the mounting member should be roughened. With this configuration, the anchoring effect of the roughened outer surface can improve the adhesive strength of the molded resin around the mounting member.

[0015] Furthermore, the method for manufacturing a film capacitor according to the present invention is characterized by comprising: a preparation step of preparing a capacitor unit and a mounting member; a housing step of housing the capacitor unit and the mounting member in a resin casting jig and fixing the mounting member to the resin casting jig with bolts; and a filling step of filling the molded resin with a preventive means for preventing the flow of molded resin into the through hole attached to the resin casting jig.

[0016] With this configuration, when the prepared capacitor unit and mounting member are placed inside the resin casting jig and molded resin is filled in, it is possible to prevent the resin from flowing into the through-hole of the mounting member and preventing the through-hole from being blocked by the resin. As a means of prevention, it is advisable to use rubber gaskets, O-rings, or lid-like members that seal the end faces of the through-holes of the resin casting jig.

[0017] Furthermore, in the housing process, it is preferable to position the mounting member relative to the resin casting jig using a positioning jig that is fitted through a fitting portion formed at the other end of the through hole of the mounting member. With this configuration, it becomes possible to fix the mounting member in a more precisely positioned state when housing it within the resin casting jig. [Effects of the Invention]

[0018] According to the present invention, a film capacitor can be firmly attached to an external mounting surface, thereby improving the reliability of the mounting. [Brief explanation of the drawing]

[0019] [Figure 1] This is a perspective view of the inside of the molded resin of a film capacitor according to one embodiment of the present invention. [Figure 2] (a) and (b) are cross-sectional and perspective views of the mounting member to be embedded in the film capacitor in Figure 1. [Figure 3]It is a perspective view showing through the capacitor unit and the attachment member inside the resin casting jig for filling the molding resin used for sealing the film capacitor of FIG. 1 with the molding resin. [Figure 4] It is a partial cut side view of the state where the attachment member is positioned on the resin casting jig for filling the molding resin of FIG. 3.

Embodiments for Carrying Out the Invention

[0020] An embodiment of the film capacitor according to the present invention will be described in detail with reference to FIGS. 1 to 4.

[0021] The structure of the film capacitor 1 according to this embodiment will be described with reference to FIGS. 1 to 4. In the following, the positive side and negative side of the x-axis may be described as the rear and front, respectively, the positive side and negative side of the y-axis may be described as the right and left, respectively, and the positive side and negative side of the z-axis may be described as the upper and lower, respectively. Further, in the following, the plan view of the film capacitor 1 seen from the positive side (upper) or negative side (lower) of the z-axis to the negative side (lower) or positive side (upper) of the z-axis may be described as the "xy plane view", the plan view of the film capacitor 1 seen from the positive side (right) or negative side (left) of the y-axis to the negative side (left) or positive side (right) of the y-axis may be described as the "xz plane view", and the plan view of the film capacitor 1 seen from the positive side (rear) or negative side (front) of the x-axis to the negative side (front) or positive side (rear) of the x-axis may be described as the "yz plane view".

[0022] As shown in FIG. 1, the film capacitor 1 includes two sets of capacitor units 1A arranged side by side, and a molding resin 2 for molding and sealing them. One set of capacitor units 1A includes a plurality (for example, seven) of metallized film capacitor elements (hereinafter referred to as "capacitor elements") 11 stacked in the z-axis direction, a first bus bar 12A in the shape of a rectangular flat plate elongated in the z-axis direction connected to one end face electrode 12 on the negative side (front) of the x-axis of each capacitor element 11, and a second bus bar 13A in the shape of a rectangular flat plate elongated in the z-axis direction similar to the first bus bar 12A and connected to the other end face electrode 13 on the positive side (rear) of the x-axis of each capacitor element 11.

[0023] The upper ends of the first busbars 12A of the two sets of capacitor units 1A are connected by a one-side lead electrode 14, and the upper ends of the second busbars 13A of the two sets of capacitor units 1A are connected by a other-side lead electrode 15. The one-side lead electrode 14 is connected to a one-side external terminal 16 provided on the upper surface of the film capacitor 1, and the other-side lead electrode 15 is connected to a other-side external terminal 17 that is arranged parallel to the one-side external terminal 16 on the upper surface of the film capacitor 1. These one-side external terminals 16 and other-side external terminals 17 are arranged in a state where they are exposed from the molded resin 2.

[0024] Furthermore, elongated mounting members 20 are embedded in the molded resin 2 at the four corners of the yz plane of the molded resin 2, penetrating the molded resin 2 in the x-axis direction. The configuration of the mounting members 20 is shown in Figure 2.

[0025] As shown in Figure 2(a), the mounting member 20 has, for example, a cylindrical metal body 20a with a circular through-hole 20b formed in the x-axis direction (see Figure 1), and as shown in Figure 2(b), the outer surface of the body 20a is roughened by knurling, for example, a diamond pattern of m0.3, to create an uneven surface. The anchoring effect of the outer surface of the body 20a with the uneven surface created by the knurling improves the adhesion strength with the molded resin 2, thereby increasing the adhesive strength between the mounting member 20 and the molded resin 2. Note that the body 20a is not limited to a cylindrical shape but may also be a rectangular prism shape.

[0026] Furthermore, as shown in Figure 2(a), a threaded portion 20c with an internal thread is formed at one end of the main body 20a, and is used to fix the mounting member 20 to a resin casting jig for mold resin filling, which will be described later and is different from the external mounting part, by screwing in a bolt. At this time, the inner diameter of the threaded portion 20c is formed to be larger than the inner diameter of the through hole 20b. The inner diameter of the threaded portion 20c is set so that when a bolt smaller than the diameter of the through hole 20b is inserted into the through hole 20b, the bolt does not interfere with the threaded portion 20c, and when inserting, for example, a long bolt into the through hole 20b of the mounting member 20 in order to attach the film capacitor 1 sealed with mold resin 2 to the external mounting part, it is possible to prevent the threaded portion 20c from interfering with the long bolt.

[0027] Furthermore, as shown in Figure 2(a), a fitting portion 20d for a positioning jig, which positions the mounting member 20 relative to a resin casting jig described later, is formed on the end face of the through hole 20b at the other end of the main body 20a by chamfering.

[0028] The resin casting jig 30, as shown in Figure 3 for example, comprises a rectangular front plate 30a on the negative x-axis side, a rectangular rear plate 30b on the positive x-axis side, and a side plate 30c that matches the outer shape of the front plate 30a and the rear plate 30b and is composed of a frame that surrounds the space sandwiched between the front plate 30a and the rear plate 30b, and has a hollow box shape. The front plate 30a and the rear plate 30b of the resin casting jig 30 are assembled to be removable from the side plate 30c, and at least the front plate 30a has one or more substantially rectangular openings 30d formed therein for injecting liquid resin.

[0029] Here, when forming the mold resin 2 by curing the liquid resin, as shown in Figure 1, the thickness of the left side of the negative y-axis (left) and the right side of the positive y-axis (right) of the side plate 30c is set to be partially thicker so that the sides of the negative y-axis (left) and positive y-axis (right) sides are concave inward, and the thickness of the top surface of the side plate 30c is set so that only the external terminals 16 and 17 on one side and the other side are exposed from the mold resin 2 from the top surface on the positive z-axis.

[0030] Then, with two sets of capacitor units 1A housed inside the box-shaped resin casting jig 30, a liquid resin, such as epoxy resin, is injected into the resin casting jig 30 through the opening 30d, and the two sets of capacitor units 1A are sealed by the molding resin 2.

[0031] At this time, the mounting member 20 is embedded in the molded resin 2 together with the capacitor unit 1A. For this purpose, as shown in Figure 4, for example, bolt insertion holes 30e in the x-axis direction through which bolts 40 can be inserted are provided at predetermined positions at the four corners of the rear plate 30b of the resin casting jig 30. The mounting member 20 is installed so that the bolt insertion holes 30e and the threaded portion 20c are in communication, and the bolts 40 (male threads) inserted through the bolt insertion holes 30e are screwed into the female threads of the threaded portion 20c, and the mounting member 20 is held perpendicular to the rear plate 30b of the resin casting jig 30. In addition, a receiving recess 30f with a diameter larger than the bolt insertion hole 30e is formed on the rear side of the rear plate 30b, which is the positive x-axis side, so that the bolt head of the bolt 40 is recessed into the rear plate 30b, and the bolt head of the bolt 40 is accommodated in the receiving recess 30f.

[0032] Furthermore, as shown in Figure 4, a ring-shaped groove 41 is formed on the front surface of the rear plate 30b of the resin casting jig 30, which is the negative x-axis side, and where the end face on the threaded portion 20c side makes contact. An O-ring 42 is fitted into this groove 41, and the end face on the threaded portion 20c side is tightly sealed against the O-ring 42, preventing liquid resin from entering the through hole 20b during filling. This O-ring 42 corresponds to the "preventive means" in the present invention.

[0033] Furthermore, in order to accurately position and fix the mounting member 20 vertically to the rear plate 30b of the resin casting jig 30, as shown in Figure 4, a housing portion 30g for the positioning jig 44 is formed on the rear side of the front plate 30a of the resin casting jig 30 on the positive x-axis side, at a position facing each bolt insertion hole 30e of the rear plate 30b. On the rear side of the housing portion 30g on the positive x-axis side, a fitting recess 30h is formed, which has a first fitting recess 30h1 that is larger in diameter than the housing portion 30g into which the flange portion of the positioning jig 44 (described later) is fitted, and a second fitting recess 30h2 that is even larger in diameter than the first fitting recess 30h1 into which the front end portion of the mounting member 20 on the negative x-axis side is fitted.

[0034] Here, the positioning jig 44 has a roughly cylindrical base 44a whose rear end, which is on the positive x-axis side, tapers to a point, and a flange 44b provided approximately in the center of the base 44a. When the base 44a is housed in the housing portion 30g, the front side of the flange 44b on the negative x-axis side abuts against the boundary between the first insertion recess 30h1 and the housing portion 30g. At the same time, the rear side of the flange 44b on the positive x-axis side abuts against the front end surface on the negative x-axis side of the mounting member 20 (main body 20a) that is fitted into the second insertion recess 30h2, and the rear side of the flange 44b on the positive x-axis side abuts against the end surface of the peripheral edge of the fitting portion 20d of the mounting member 20.

[0035] Furthermore, a bolt insertion hole 30i in the x-axis direction is provided through the front side of the front plate 30a of the resin casting jig 30 on the negative x-axis side, communicating with the housing portion 30g. A bolt 45 is inserted through the bolt insertion hole 30i and screwed into a threaded hole formed at the front end of the positioning jig 44 on the negative x-axis side. As a result, the positioning jig 44 and the mounting member 20 are fixed in a state where they are held perpendicular to the front plate 30a and rear plate 30b of the resin casting jig 30, and the mounting member 20 is accurately positioned and fixed to the resin casting jig 30.

[0036] Here, the screwing of the bolt 45 causes the rear surface of the flange portion 44b on the positive x-axis side to be in close contact with the peripheral end face of the fitting portion 20d of the mounting member 20. This close contact prevents the liquid resin from entering the through hole 20b of the mounting member 20. Therefore, similar to the O-ring 42, the flange portion 44b of the positioning jig 44 functions as a "preventive measure" in this invention.

[0037] Then, as a method for manufacturing the film capacitor 1, a capacitor unit 1A and a mounting member 20 are prepared (preparation step), and in order to position the prepared mounting member 20 in a predetermined location, the mounting member 20 is fixed inside the resin casting jig 30 together with the capacitor unit 1A by screwing bolts 40 and 45 (storage step), and liquid resin such as epoxy resin is filled into the resin casting jig 30 (filling step).

[0038] After the liquid resin hardens, the bolts 40 and 45 are removed, the resin casting jig 30 is disassembled, and the two sets of capacitor units 1A and mounting members 20 molded with the molding resin 2 are taken out, thereby completing the manufacture of the film capacitor 1 as shown in Figure 1.

[0039] Therefore, according to the above embodiment, since the mounting member 20 is embedded so as to penetrate the molded resin 2, the contact area with the molded resin 2 is larger compared to conventional fasteners embedded on the surface of the molded resin, and the adhesive force between the mounting member 20 and the surrounding molded resin 2 is strengthened. For this reason, for example, by inserting a long bolt through the through hole 20b of the mounting member 20, the film capacitor 1 can be firmly attached to an external mounting part via the mounting member 20, thereby improving the reliability of attachment to an external mounting part.

[0040] Furthermore, by screwing a bolt 40 into the threaded portion 20c formed on one end (rear end) of the through hole 20b, the mounting member 20 can be fixed to a resin casting jig 30 that is different from the external mounting part. Therefore, when filling the mold resin 2, the mounting member 20 can be accurately positioned relative to the resin casting jig 30, and the mounting member 20 can be embedded in the mold resin 2 without misalignment.

[0041] Furthermore, because the inner diameter of the threaded portion 20c is larger than the inner diameter of the through hole 20b, when inserting, for example, a long bolt into the through hole 20b of the mounting member 20 in order to attach the film capacitor 1 to an external mounting part, the threaded portion 20c does not interfere with the long bolt, allowing the mounting work to be carried out smoothly.

[0042] Furthermore, since a fitting portion 20d for the positioning jig 44 is formed on the other end (front end) of the through hole 20b of the mounting member 20, when the rear end of the mounting member 20 is fixed to the resin casting jig 30, the positioning jig 44 can be fitted into the fitting portion 20d at the front end, thereby allowing the mounting member 20 to be held vertically relative to the resin casting jig 30 and fixed in a more precisely positioned state.

[0043] Furthermore, since the outer surface of the mounting member 20 is roughened with knurling, such as a diamond pattern, the anchoring effect of the roughened outer surface can improve the adhesive strength of the molded resin 2 around the mounting member 20. Note that the irregularities on the outer surface of the mounting member 20 are not limited to those formed by diamond pattern processing.

[0044] It should be noted that the present invention is not limited to the above-described configuration, and various design modifications can be made within the scope of the matters described in the claims.

[0045] For example, in the embodiment described above, the case in which mounting members 20 are embedded in four locations in the molded resin 2 was explained, but the number of mounting members 20 to be embedded is not particularly limited, and the method can also be applied when mounting members 20 are embedded in at least one location.

[0046] Furthermore, although the shape of the molded resin 2 in the above-described embodiment was explained as having the sides on the negative y-axis side (left) and the positive y-axis side (right) concave inward, as shown in Figure 1, the outer shape of the molded resin 2 may be any shape, such as a rectangular parallelepiped.

[0047] Furthermore, the configuration of the capacitor unit molded with the molding resin 2 is not limited to two sets as in the embodiment described above, but may consist of one set or three or more sets, and the number of capacitor elements 11 constituting each set of capacitor units is not limited to seven as shown in Figure 1.

[0048] Furthermore, instead of the O-ring used as a preventative measure in this invention, other rubber gaskets or lid-like members may be provided.

[0049] The present invention is widely applicable to film capacitors in which a capacitor unit including a capacitor element is sealed with a molding resin. [Explanation of Symbols]

[0050] 1…Film capacitor 1A ... Capacitor unit 2…Mold resin 20 ... Mounting parts 20b...Through hole 20c ... Threaded section 20d ... Fitting part 30 ... Resin casting jig 42 ... O-ring (preventive measure) 44 ... Positioning jig 44b...Flame (preventive means)

Claims

1. In a film capacitor in which a capacitor unit including a capacitor element is sealed with a molded resin, It is equipped with a mounting member for attaching to an external mounting surface, The aforementioned mounting member is embedded in the molded resin so as to penetrate the molded resin in a predetermined penetrating direction, and has a through hole extending in the penetrating direction, with both ends of the through hole exposed from the molded resin.

2. The through hole has a threaded portion at one end with an internal thread formed therein. The film capacitor according to claim 1, characterized in that the threaded portion fixes the mounting member to a resin casting jig for mold resin filling, which is different from the external mounting portion, by screwing in a bolt.

3. The film capacitor according to claim 2, characterized in that the inner diameter of the threaded portion is larger than the inner diameter of the through hole.

4. The film capacitor according to claim 2, characterized in that a fitting portion for a positioning jig for positioning the mounting member relative to the resin casting jig is formed at the other end of the through hole of the mounting member.

5. The film capacitor according to claim 1, characterized in that the outer surface of the mounting member is roughened.

6. A method for manufacturing a film capacitor according to any one of claims 2 to 4, Preparation steps include preparing the capacitor unit and the mounting member, A housing step in which the capacitor unit and the mounting member are housed in the resin casting jig, and the mounting member is fixed to the resin casting jig by the bolts, A filling step in which the mold resin is filled with a resin casting jig with a preventative means for preventing the flow of the mold resin into the through hole attached to the resin casting jig. A method for manufacturing a film capacitor, characterized by comprising the following features.

7. The method for manufacturing a film capacitor according to claim 6, characterized in that the housing step further involves positioning the mounting member relative to the resin casting jig by a positioning jig fitted into a fitting portion formed at the other end of the through hole of the mounting member.

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