JP7508382B2 - Capacitor - Google Patents

Description

This invention relates to a capacitor in which the capacitor element is sealed with resin.

Patent document 1 discloses a capacitor that includes a capacitor element, two electrode plates connected to the capacitor element, and resin that seals the capacitor element, and that can efficiently cool one of the electrode plates by exposing the substrate portion of one of the electrode plates to the outside of the resin.

JP 2019-096713 A

However, in the capacitor of Patent Document 1, most of the other electrode plate is located inside the resin, so a separate measure is required to efficiently cool the other electrode plate. In addition, when placing the other electrode plate, cooling member, or other conductive member close to the substrate part exposed outside the resin, it is necessary to separately interpose an insulator such as insulating paper between the substrate part, which makes assembly complicated.

The present invention aims to provide a capacitor that is easy to assemble and can efficiently cool both the positive and negative electrode plates.

The capacitor of the present invention comprises a capacitor element 2, a first electrode plate 3 and a second electrode plate 4 connected to the capacitor element 2, a case 5 that houses the capacitor element 2, and a resin 6 filled in the case 5. The first electrode plate 3 and the second electrode plate 4 comprise insulating substrate portions 31, 41 that cover the capacitor element 2 from above, the substrate portion 41 of the second electrode plate 4 comprises an upper stage portion 41b and a lower stage portion 41c that overlaps with the substrate portion 31 of the first electrode plate 3, the upper surface of the upper stage portion 41b and the upper surface of the substrate portion 31 of the first electrode plate 3 are located on the same plane, and the upper surfaces located on the same plane are exposed outside the resin.

In the above capacitor, it is preferable that at least one of the first electrode plate 3 and the second electrode plate 4 has a leg portion 32 (and/or 42) for exposing the substrate portion 31, 41 to the outside of the resin. It is also preferable that at least one of the first electrode plate 3 and the second electrode plate 4 has a tongue portion 35 (and/or 45) that extends from the substrate portion 31 (and/or 41) toward the inside of the case 5 and is embedded in the resin.

The capacitor of the present invention can efficiently cool both the positive and negative electrode plates because the top surface of the substrate portion of the first electrode plate and the top surface of the upper stage portion of the substrate portion of the second electrode plate are exposed outside the resin. In addition, because the top surfaces are located on the same plane, they can be easily brought into contact when using a cooling member for cooling. In addition, because the substrate portion is insulated, there is no need to consider insulation when stacking the substrate portions together or when bringing a cooling member into contact with the substrate portion, making assembly simple.

If at least one of the first electrode plate and the second electrode plate has legs for exposing the substrate portion outside the resin, the substrate portion can be reliably exposed. If at least one of the first electrode plate and the second electrode plate has a tongue that extends from the substrate portion toward the inside of the case and is embedded in the resin, the inside of the capacitor can be cooled more efficiently.

1 is an exploded perspective view showing a capacitor according to an embodiment of the present invention. FIG. 2 is a perspective view of the first electrode plate viewed from below. FIG. 4 is a perspective view of the second electrode plate viewed from below. FIG. 2 is a perspective view of the capacitor with the resin omitted. FIG. 2 is a cross-sectional view of a capacitor.

Next, one embodiment of the capacitor of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the capacitor 1 of the present invention comprises a capacitor element 2, a first electrode plate 3 connected to one electrode of the capacitor element 2, a second electrode plate 4 connected to the other electrode of the capacitor element 2, a case 5 that houses the capacitor element 2, and resin 6 (see FIG. 5) that fills the case 5. Each of the above components will be described below, but the concept of "upper and lower" refers to the time of manufacture, or more specifically, the time of resin filling, and does not necessarily define the upper and lower during use.

The capacitor element 2 is a film capacitor formed by winding a metallized film in which metal is vapor-deposited on the surface of an insulating film, and as shown in FIG. 1, electrode portions 2a and 2b formed by spraying metal are formed on both axial ends. When viewed from the axial direction, the capacitor element 2 is shaped like a bale, specifically, R (radius) is provided at the four corners, and a side surface 2c consisting of a flat portion 2c1 and a curved portion 2c2 is formed between the electrode portions 2a and 2b (peripheral surface). A plurality of electrode portions 2a, 2a on one side and electrode portions 2b, 2b on the other side are arranged in parallel in the axial direction (four in the figure) so that they face each other. Therefore, the electrode portion 2a on one side and the electrode portion 2b on the other side are arranged alternately. In addition, a first lead wire 21 for connecting to the first electrode plate 3 is connected to the electrode portion 2a on one side, and a second lead wire 22 for connecting to the second electrode plate 4 is connected to the electrode portion 2b on the other side. These lead wires 21 and 22 protrude upward.

The first electrode plate 3 has a substrate portion 31 that covers the capacitor element 2 from above, legs 32 for exposing the substrate portion 31 to the outside of the resin, a connection portion 33 that connects to the capacitor element 2, an external connection terminal 34 that connects to an external device (not shown), and a tongue piece 35 for cooling the inside of the capacitor (see Figures 1 and 2).

The substrate 31 is generally rectangular in plan view, with a length that is approximately the same as the longitudinal length of the capacitor elements 2 arranged side by side, and a width that is approximately the same as the width of the flat portion 2c1 of the capacitor element 2 (the distance between the curved portions 2c2, 2c2), and is arranged to face the flat portions 2c1 of the capacitor elements 2 arranged side by side. The substrate 31 has an opening 31a at a position facing the electrode portions 2a, 2b of the capacitor element 2 in plan view. Of the four openings provided in total, the leg 32 extends downward from the inner edge (side parallel to the longitudinal direction of the substrate 31) of the opening 31a facing the first lead wire 21. In addition to the opening 31a, the leg 32 also extends from the outer edge of the substrate 31 and the side facing the first lead wire 21 (the short side on the right side in FIG. 2). The connection portion 33 extends horizontally from the tip of the leg 32 and has a connection hole through which the first lead wire 21 can be inserted. The external connection terminal 34 extends horizontally from one long side and the short side from which the leg 32 does not extend of the outer edge of the substrate 31. The tongue 35 extends downward from the inner edge of the opening 31a from which the leg 32 does not extend (the side perpendicular to the length of the substrate 31). In other words, the substrate 31 is the extension source of the leg 32, the connection portion 33, the external connection terminal 34, and the tongue 35.

The second electrode plate 4 includes a substrate portion 41 that covers the capacitor element 2 from above, a leg portion 42 for exposing the substrate portion 41 to the outside of the resin, a connection portion 43 that connects to the capacitor element 2, an external connection terminal 44 that connects to an external device (not shown), and a tongue piece 45 for cooling the inside of the capacitor (see Figures 1 and 3).

The substrate portion 41 is generally rectangular in plan view, with a length that is generally the same as the length of the capacitor elements 2 arranged in parallel in the longitudinal direction, and a width that is wider than the width of the capacitor elements 2 in the flat direction, and is arranged so as to face the flat portions 2c1 of the capacitor elements 2 arranged in parallel. In addition, a step portion 41a is provided generally parallel to the long side, and this step portion 41a divides the substrate portion 41 into an upper step portion 41b and a lower step portion 41c. The vertical height (step) of the step portion 41a is generally equal to the thickness of the first electrode plate 3. This is to position the upper surface of the substrate portion 31 of the first electrode plate 3 and the upper surface of the upper step portion 41b of the second electrode plate 4 on the same plane when the substrate portion 31 of the first electrode plate 3 is superimposed on the lower step portion 41c from above (see FIG. 5). The lower step portion 41c has an opening 41d at a position facing the opening 31a of the first electrode plate 3 in plan view. Of the four openings 41d, the legs 42 extend downward from the inner edge (side parallel to the length direction of the substrate 41) of the opening 41d facing the second lead wire 22. The connection portion 43 extends horizontally from the tip of the leg 42 and has a connection hole through which the second lead wire 22 can be inserted. The external connection terminal 44 extends horizontally from the long side of the lower stage 41c side of the substrate 41 and the short side of the upper stage 41b side. The external connection terminal 34 of the first electrode plate 3 and the external connection terminal 44 of the second electrode plate 4 are shifted from each other in the horizontal direction and do not overlap. The tongue piece 45 extends downward from the inner edge (side perpendicular to the length direction of the substrate 41) of the opening 41d from which the legs 42 do not extend and from the long side of the upper stage 41b. That is, the base portion 41 is the base from which the legs 42, the connection portion 43, the external connection terminal 44, and the tongue piece 45 extend.

The first electrode plate 3 and the second electrode plate 4 are formed by cutting a metal plate such as copper or aluminum into a predetermined shape and bending it appropriately. In addition, at least the substrate portion 31 of the first electrode plate 3 and the substrate portion 41 of the second electrode plate 4 are insulated. Parts that are in close proximity to or in contact with the capacitor element 2 or the case 5, specifically, the base ends of the legs 32, 42, the tongue pieces 35, 45, and the external connection terminals 34, 44 may be insulated. Note that the parts that are in contact with the first lead wire 21, the second lead wire 22, and the terminals of the external device are not insulated because they require electrical connection. Alternatively, the insulating material may be removed as necessary after the entire electrode plate is insulated. The insulating treatment is performed by applying an insulating paint such as polyimide or polyamide. However, the insulating material may be electrocoated, an insulating sheet may be attached, or the insulating material may be covered with an insulating heat shrink tube. In short, it is sufficient if it can be integrated (adhered) with the electrode plate and ensure insulation.

As shown in FIG. 1, the case 5 has a bottom 5a that is approximately rectangular in plan view, and side walls 5b that surround the bottom 5a on all four sides. The top end of the case 5 is open, and a space capable of housing the capacitor element 2 is formed inside. The upper end of the side walls 5b, which abut against or are close to the lower surfaces of the electrode plates 3 and 4, is a double wall 5b1 that is open at the top (see FIG. 5). This is to prevent the resin 6 filled in the case 5 from flowing out of the case 5 through the gap between the upper end of the side walls 5b and the lower surfaces of the electrode plates 3 and 4. The material of the case 5 is a non-conductive material such as synthetic resin. However, if the electrode plates 3 and 4 that are insulated at the points abutting against or close to the case 5 are used, a conductive material such as metal may be used.

The resin 6 filled in the case 5 is, for example, an epoxy resin. However, it is not limited to this, and various known resins such as urethane resin can be used. It is preferable to use a resin with excellent moisture resistance and high thermal conductivity. Furthermore, changing the resin thickness (the distance from the resin surface to the capacitor element) depending on the type and characteristics of the resin used is naturally something that should be taken into consideration in the design.

Next, a method for manufacturing the capacitor 1 will be described. First, while connecting the connection portion 43 of the second electrode plate 4 to the second lead wire 22, the substrate portion 41 of the second electrode plate 4 is placed from above on the flat portion 2c1 of the multiple capacitor elements 2 arranged side by side. In this state, a gap is formed between the flat portion 2c1 of the capacitor element 2 and the substrate portion 41 of the second electrode plate 4 by at least the height of the leg portion 42.

Next, the connection portion 33 and the leg portion 32 of the first electrode plate 3 are passed through the opening 41d of the second electrode plate 4, and the connection portion 33 and the first lead wire 21 are connected. In this state, the first electrode plate 3 is further moved downward, and the substrate portion 31 of the first electrode plate 3 is overlapped from above on the upper surface of the lower stage portion 41c of the second electrode plate 4, and the upper surface of the substrate portion 31 of the first electrode plate 3 and the upper surface of the upper stage portion 41b of the second electrode plate 4 are positioned on the same plane (flush). In this state, the capacitor element 2 is covered from above by the substrate portion 31 of the first electrode plate 3 and the substrate portion 41 of the second electrode plate 4. It can also be said that this state is such that the flat portion 2c1 of the capacitor element 2 faces the substrate portions 31 and 41.

Next, the capacitor element 2 is housed in the case 5. At this time, the capacitor element 2 is housed so that it is located on the bottom 5a side of the case 5, and the first electrode plate 3 and the second electrode plate 4 are located on the opening 5c side of the case 5. Then, the case 5 is filled with resin, and the capacitor element 2 is sealed to complete the manufacture of the capacitor 1. The resin surface and the opening 5c of the case 5 (the plane formed between the upper ends of the side wall portions 5b) are approximately parallel. The opening 5c of the case 5 (the plane formed between the upper ends of the side wall portions 5b) and the substrate portions 31, 41 of the electrode plates 3, 4 are also approximately parallel.

As shown in FIG. 5, the upper surface of the substrate portion 31 of the first electrode plate 3 and the upper surface of the upper step portion 41b of the second electrode plate 4 are exposed to the outside of the resin. A cooling member (not shown) may be placed in contact with this exposed upper surface. Various cooling members are possible, such as a thermal pad, a water-cooled pipe, or a heat sink. The lower surfaces of the substrate portions 31 and 41 are also exposed to the outside of the resin. In other words, the entire substrate portions 31 and 41 are exposed to the outside of the resin. However, it is not necessary to expose the entire substrate portion. The external connection terminals 34 and 44 are exposed to the outside of the resin, and the legs 32 and 42, the connection portions 33 and 43, and the tongues 35 and 45 are embedded in the resin.

In the capacitor 1 having the above configuration, the upper surfaces of the substrate parts 31, 41 of both the positive and negative electrode plates 3, 4 are exposed to the outside of the resin, so that a sufficient heat dissipation area is ensured, and both electrode plates 3, 4 can be cooled efficiently. In addition, since the side wall part 5b of the case 5 and the like are not interposed between the capacitor element 2 and the substrate parts 31, 41 of the electrode plates 3, 4 (specifically, the parts from which the connection parts 33, 43 extend (the inner edges of the openings 31a, 41d)), the capacitor element 2 and the electrode plates 3, 4 are directly connected, and the connection distance between the capacitor element 2 and the substrate parts 31, 41 is short, and the capacitor element 2 is also cooled more easily than when, for example, the side wall part 5b of the case 5 is interposed between the capacitor element 2 and the substrate parts 31, 41 (specifically, the parts from which the connection parts 33, 43 extend) and the side wall part 5b is bypassed for connection. In addition, because the tongues 35, 45 extend from the substrate 31, 41 into the resin, the heat in the resin can be efficiently transferred to the substrate 31, 41, and the inside of the capacitor can be cooled smoothly. Furthermore, because the side wall 5b of the case 5 is not interposed between the tongues 35, 45 and the capacitor element 2, the reach to the resin 6 is short.

In addition, since both the substrate portion 31 of the first electrode plate 3 and the substrate portion 41 of the second electrode plate 4 are insulated before assembly, there is no need to consider the creepage distance between the substrate portion 31 of the first electrode plate 3 and the substrate portion 41 of the second electrode plate 4. For example, the lower surface of the substrate portion 31 of the first electrode plate 3 can be abutted against the upper surface of the lower portion 41c of the second electrode plate 4. As a result, design constraints are relaxed, such as ensuring the cross-sectional area of the electrode plates 3 and 4 to improve current density. Also, there is no need for assembly work such as insulating paper, which reduces labor and costs. Furthermore, it becomes easier to use a metal case.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the above embodiment, both the first electrode plate 3 and the second electrode plate 4 have legs 32, 42, but only one of them may have legs. In addition, the legs 32, 42 may be supported by the bottom 5a of the case 5, not by the capacitor element 2. Furthermore, without providing legs, the substrate parts 31, 41 and the external connection terminals 34, 44 may be hooked to the upper end of the side wall part 5b of the case 5, so that the substrate parts 31, 41 are exposed to the outside of the resin. In addition, both the first electrode plate 3 and the second electrode plate 4 have tongue pieces 35, 45, but only one of them may have tongue pieces.

Although the capacitor has been described as having multiple capacitor elements, it may have only one capacitor element. The number of openings 31a, 41d is changed as appropriate according to the number of capacitor elements, specifically the number of electrode portions 2a, 2b. The capacitor elements are not limited to wound types, and may be laminated types. The type of capacitor is not limited to film capacitors, electrolytic capacitors, ceramic capacitors, etc. The lead wires 21, 22 do not necessarily need to be provided, and the connection portions 33, 43 may be directly connected to the electrode portions 2a, 2b of the capacitor element 2.

REFERENCE SIGNS LIST 1 Capacitor 2 Capacitor element 2a One electrode portion 2b The other electrode portion 2c Side surface 2c1 Flat portion 2c2 Curved surface portion 21 First lead wire 22 Second lead wire 3 First electrode plate 31 Substrate portion 31a Opening 32 Leg portion 33 Connection portion 34 External connection terminal 35 Tongue piece 4 Second electrode plate 41 Substrate portion 41a Step portion 41b Upper step portion 41c Lower step portion 41d Opening 42 Leg portion 43 Connection portion 44 External connection terminal 45 Tongue piece 5 Case 5a Bottom portion 5b Side wall portion 5b1 Double wall 5c Opening 6 Resin

Claims (3)

A capacitor element;
a first electrode plate and a second electrode plate connected to the capacitor element;
A case for accommodating a capacitor element;
and a resin filled in the case,
The first electrode plate and the second electrode plate include an insulating substrate portion that covers the capacitor element from above,
A capacitor characterized in that the substrate portion of the second electrode plate has an upper stage portion and a lower stage portion overlapping with the substrate portion of the first electrode plate, the upper surface of the upper stage portion and the upper surface of the substrate portion of the first electrode plate are located on the same plane, and the upper surfaces located on the same plane are exposed to the outside of the resin. The capacitor of claim 1, wherein at least one of the first electrode plate and the second electrode plate has a leg portion for exposing the substrate portion outside the resin. A capacitor as claimed in claim 1 or 2, in which at least one of the first and second electrode plates has a tongue extending from the substrate portion towards the inside of the case and embedded in the resin.

Images