Capacitor

Abstract

To provide a capacitor which has high insulation reliability even under environment that vibration is repeatedly input, and can reduce an inductance.SOLUTION: A capacitor includes a capacitor element stored in a resin case, and two bus bars connected to the capacitor element. The capacitor has a lamination part where the two bus bars are superposed across an insulation sheet, the lamination part has a through hole in the lamination direction and has a fixing member for fixing the lamination part to the resin case through the through hole, a part where the fixing member is brought into contact with at least the bus bars has insulation property, and accordingly the capacitor has high insulation reliability even under environment that vibration is repeatedly input, and can reduce an inductance.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a capacitor, and more particularly to a capacitor with reduced inductance. [Background technology]

[0002] The characteristics of a capacitor include resistance and inductance components in addition to capacitance. Both the resistance and inductance degrade the performance of a capacitor, so capacitors are generally designed to have small values.

[0003] Patent Document 1 describes a capacitor in which two bus bars are overlapped and insulated by sandwiching an insulating sheet between the bus bars, thereby reducing the gap between the two bus bars and reducing the equivalent DC inductance (ESL).

[0004] Furthermore, the holder that holds the ends of the two overlapping bus bars prevents misalignment between the bus bars and the insulating sheet and makes it possible to increase the area where the two bus bars overlap, thereby further reducing the ESL. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent 6575869 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the capacitor described in Patent Document 1, the overlapping portion of the two bus bars is not fixed to the case. Therefore, in an environment where repeated vibrations are input, such as a vehicle power supply device, the overlapping portion of the bus bars vibrates, easily causing the bus bars and the insulating sheet to become misaligned and reducing insulation reliability, making it difficult to increase the area of ​​the overlapping portion of the two bus bars.

[0007] The present invention has been made in consideration of the problems associated with the conventional technology, and an object of the present invention is to provide a capacitor that has high insulation reliability and can reduce inductance even in an environment where repeated vibrations are input. [Means for solving the problem]

[0008] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that the above-mentioned object can be achieved by providing a through hole in a laminated portion in which two bus bars are overlapped with an insulating sheet in between, and using an insulating fixing member to fix the laminated portion to a resin case via the through hole, thereby completing the present invention.

[0009] That is, the capacitor of the present invention includes a capacitor element accommodated in a resin case, and two bus bars connected to the capacitor element. The laminated portion has an insulating sheet sandwiched between two bus bars, the laminated portion has a through hole in the stacking direction, and a fixing member passes through the through hole and fixes the laminated portion to the resin case, and at least the portion of the fixing member that comes into contact with the bus bar is insulating. Effect of the Invention

[0010] According to the present invention, a through hole is provided in the laminated portion where two bus bars are overlapped with an insulating sheet in between, and the bus bars are fixed to a resin case via this through hole with an insulating fixing member. This makes it possible to provide a capacitor that has high insulation reliability even in an environment where repeated vibrations are input, and can reduce inductance. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view showing an example of a capacitor of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing an example of a capacitor of the present invention taken along the line AA′ in FIG. [Diagram 3]2 is a cross-sectional view showing another example of the capacitor of the present invention taken along the line AA' in FIG. [Figure 4] 2 is a cross-sectional view showing still another example of the capacitor of the present invention taken along the line AA' in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The capacitor of the present invention will now be described in detail. As shown in FIG. 1, the capacitor of the present invention comprises a capacitor element (1), a resin case (2) that houses the capacitor element, and two bus bars (3a, 3b) connected to the capacitor element.

[0013] The capacitor element (1) shown in FIG. 1 has electrodes (11) on the upper and lower surfaces. One bus bar (3a), for example a P bus bar, is connected to the electrode on the lower surface of the capacitor element, and the other bus bar (3b), for example an N bus bar, is connected to the electrode on the upper surface.

[0014] One bus bar (3a) connected to the underside of the capacitor element wraps around the capacitor element (1) and the other bus bar (3b) and projects above the other bus bar (3b) along the inner wall of the resin case (2).

[0015] In FIG. 1, for convenience, one bus bar (3a) is shown divided into the lower side of the capacitor element (1) and the upper side of the other bus bar (3b); however, as shown in FIG. 2, it is continuous from the lower side of the capacitor element (1) to the upper side of the other bus bar (3b). Additionally, the electrodes (11) of the capacitor element (1) may be on the side surfaces.

[0016] The portion of one bus bar (3a) that protrudes higher than the other bus bar (3b) overlaps with the other bus bar (3b) to form a laminated portion (31), and an insulating sheet (4) is provided between the one bus bar (3a) and the other bus bar (3b) of the laminated portion to provide insulation between them.

[0017] In this laminated portion (31), one bus bar (3a) and the other bus bar (3b) are the same size and overlap each other exactly to maintain symmetry, thereby reducing the equivalent DC inductance (ESL).

[0018] The insulating sheet (4) is not particularly limited as long as it can prevent a short circuit between the two bus bars, and for example, a resin sheet or insulating paper can be used.

[0019] Moreover, the other bus bar (3b) of the laminated portion (31) abuts against the edge of the resin case (2) and covers at least a part of the opening of the resin case (2).

[0020] In this manner, since the laminated portion (31) is disposed on the opening surface of the resin case (2), even if the area of ​​the laminated portion (31) is made as large as the opening surface of the resin case (2), there is no effect on the size of the entire capacitor, and it is possible to achieve both reduced ESL and miniaturization.

[0021] Further, a through hole (32) is provided in the laminated portion (31) at a position corresponding to the edge of the resin case (2), and a fixing member (5) passes through this through hole (32) to fix the laminated portion (31) to the resin case (2).

[0022] In the capacitor of the present invention, the laminated portion (31) covers the opening of the resin case (2) and can be fixed to the edge of the resin case (2), so that even if vibration is input, the laminated portion (31) will not vibrate independently.

[0023] In addition, since the fixing member (5) passes through the through hole (32) of the laminated portion (31), no misalignment occurs between the two bus bars or between the two bus bars (3a, 3b) and the insulating sheet (4), thereby improving insulation reliability. In addition, in FIG. 1, the laminated portion (31) is fixed at four points, but vibration of the laminated portion (31) can be suppressed if it is fixed at three or more points.

[0024] Furthermore, since at least the portions of the fixing member (5) that come into contact with the bus bars (3a, 3b) are insulating, the two bus bars (3a, 3b) are prevented from being short-circuited via the fixing member (5).

[0025] It is preferable that the inner circumferential surface of the through hole (32) is flush with the two bus bars (3a, 3b). Since the inner circumferential surface is flush and the two bus bars (3a, 3b) are not misaligned, the projected areas of the two bus bars (3a, 3b) are the same at the fixed portion, thereby reducing the equivalent DC inductance (ESL).

[0026] Next, a method for fixing the laminated portion (31) to the resin case (2) using the fixing member (5) will be described.

[0027] Examples of the fixing member (5) include screws, rivets, and adhesives. Metal screws and rivets are preferably used because they can provide a large fastening force and can firmly fix the laminated portion (31) to the resin case (2).

[0028] When the fixing member (5) is made of an insulating material such as resin, even if the fixing member (5) is directly passed through the through hole (32) as shown in FIG. 2, a short circuit via the fixing member (5) does not occur. Therefore, for example, a plastic screw can be screwed into a plastic case to fix the fixing member (5).

[0029] When fixing with an adhesive, the adhesive can be poured into the through hole (32) to fix it to the resin case (2).

[0030] If the fixing members (5) are metal screws or rivets, the two bus bars (3a, 3b) would be short-circuited via the fixing members (5), so an insulating fixing plate (51) is used to prevent the screws or rivets from coming into direct contact with the bus bars.

[0031] The insulating fixing plate (51) may be a flat or hat-shaped fixing plate having a through hole (52), and the insulating fixing plate (51) may be made of a material such as resin or ceramic.

[0032] When a flat fixing plate is used, as shown in FIG. 3, the through hole (52) of the insulating fixing plate (51) is aligned with the through hole (32) of the laminated portion (31) so that the insulating fixing plate (51) is abutted against the surface of the laminated portion (31), the shafts of screws or rivets are passed through these through holes (32, 52), and the seating surfaces of the screws or rivets are pressed against the laminated portion (31) via the insulating fixing plate (51) to fix it to the eaves (21) provided on the edge of the resin case (2).

[0033] In this case, if there is a gap between the shaft of the screw or rivet and the inner surface of the through hole (32) of the laminated portion (31) and the shaft and the inner surface of the through hole (32) are not in contact with each other, a short circuit between the two bus bars (3a, 3b) can be prevented. However, it is preferable to provide a guide portion (22) on the eaves (21) of the resin case (2) that protrudes toward the laminated portion (31).

[0034] By fitting the through hole (32) of the laminated portion (31) into the guide portion (22), not only can a short circuit between the two bus bars (3a, 3b) be prevented, but also misalignment of the bus bars (3a, 3b) of the laminated portion (31) and the insulating sheet (4) can be prevented.

[0035] When using a fixing plate having a hat-shaped cross section, as shown in Figure 4, the hat-shaped crown portion (53), i.e., the portion forming the recess in Figure 4, is inserted into the through hole (32) of the stacked portion (31), and the hat-shaped brim portion (54) is abutted against the surface of the stacked portion (31).

[0036] Then, the shaft of a screw or rivet is passed through the through hole (52) in the crown portion, and the seat surface is abutted against the crown portion (53) to fix the laminated portion (31) to the eaves (21) provided on the edge of the resin case (2).

[0037] In the case of a fixing plate having a hat-shaped cross section, the crown portion (53) fits into the through hole (32) of the laminated portion (31) to prevent a short circuit between the axis of the screw or rivet and the bus bar (3a, 3b), so the guide portion (22) is not necessarily required. However, providing the guide portion (22) as in Figure 3 makes positioning easier.

[0038] Furthermore, when a fixing plate having a hat-shaped cross section is used, the heads of the screws or rivets fit inside the crown portion (53), so that the overall height of the capacitor can be reduced, enabling miniaturization.

[0039] The capacitor of the present invention can be suitably used as a smoothing capacitor for a power conversion device by connecting one end of the laminated portion, for example, the front side of the pages in Figures 2 to 4, to a battery, and connecting the other end of the laminated portion, for example, the rear side of the pages in Figures 2 to 4, to a power module. [Explanation of symbols]

[0040] 1 Capacitor element 11 electrodes 2 Resin case 21 Eaves 22 Guide section 3 Busbar 31 Laminated section 32 Through hole 4. Insulation sheet 5 Fixing material 51 Insulating fixing plate 52 Through hole 53 Crown section 54 Brim

Claims

1. A capacitor element accommodated in a resin case; and two bus bars connected to the capacitor element, a laminated portion in which the two bus bars are overlapped with an insulating sheet sandwiched therebetween; The laminated portion has a through hole in the lamination direction, a fixing member that passes through the through hole and fixes the laminated portion to the resin case, A capacitor, wherein at least a portion of the fixing member that comes into contact with the bus bar has insulating properties.

2. 2. The capacitor according to claim 1, wherein an inner peripheral surface of the through hole formed in the laminated portion is flush.

3. The fixing member includes a screw and / or a rivet and an insulating fixing plate, the screws and / or rivets are electrically conductive; 3. The capacitor according to claim 1, wherein the seating surface of the screw and / or rivet abuts against the surface of the laminated portion via the insulating fixing plate, and the axis of the screw and / or rivet is not in contact with the inner surface of the through hole.

4. The insulating fixing plate has a hat-shaped cross section, The flange portion of the insulating fixing plate abuts against the surface of the laminated portion, The crown portion of the insulating fixing plate is inserted into the through hole, 4. The capacitor according to claim 3, wherein the seat of the screw and / or rivet abuts a crown portion in the through hole.

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