Capacitor

Abstract

A capacitor 1 includes: a capacitor element 10 that has a first end face electrode 12 and a second end face electrode 13; a first bus bar 2 that has a first body part 20 and a first lead-out part having a first external connection terminal 22; a second bus bar 3 that has a second body part 30 and a second lead-out part having a second external connection terminal 32; a case 5; a sealing resin 6 that seals the capacitor element 10, the first bus bar 2, and the second bus bar 3 in a state of being housed in the case 5; and an insulation resin member 4 that is vacuum-molded, insulates the first external connection terminal 22 from the second external connection terminal 32, and is set such that the inter-terminal distance between the first lead-out part and the second lead-out part opposite to each other and having the insulation resin member 4 therebetween is 0.8 mm or less, and the creepage distance between the adjacent first lead-out part and the second lead-out part is rated voltage × 0.005 mm to rated voltage × 0.007 mm.

Description

capacitor

[0001] The present invention relates to a capacitor.

[0002] Conventionally, a film capacitor has been known that includes a capacitor element, a pair of bus bars, an insulating member, a case, and a sealing resin (see, for example, International Publication No. 2017 / 146013). The capacitor element has a pair of end electrodes. The pair of bus bars are electrically connected to the pair of end electrodes of the capacitor element. The insulating member is disposed between the pair of bus bars to insulate each of the pair of bus bars. The case accommodates the capacitor element, a portion of the pair of bus bars, and a portion of the insulating member in an accommodating space. The accommodating space accommodating the capacitor element, a portion of the pair of bus bars, and a portion of the insulating member is filled with sealing resin.

[0003] Film capacitors are widely used in inverter equipment. As inverter equipment becomes more powerful and efficient, it becomes necessary to reduce the parasitic inductance of film capacitors. To achieve this, it is necessary to reduce the thickness of the insulating material so as to shorten the distance between the external connection terminals formed on each of a pair of bus bars.

[0004] The insulating members in conventional film capacitors are generally formed by injection molding of resin, which limits how thin the insulating members can be made, making it difficult to reduce the parasitic inductance below a desired value.

[0005] It is also possible to form the insulating member from insulating paper instead of resin molding. However, while insulating paper is thin and can shorten the distance between a pair of bus bars (external connection terminals), it is difficult to provide three-dimensional insulation between the pair of bus bars, making it difficult to ensure creepage distance between the pair of bus bars. Furthermore, because insulating paper lacks strength when attached to the bus bars, it is difficult to handle and requires a process such as attaching it to the bus bars in advance, which reduces work efficiency.

[0006] An object of the present invention is to provide a capacitor that can reduce parasitic inductance while ensuring a creepage distance between a pair of bus bars.

[0007] A first aspect of the present invention provides a capacitor element having a first end surface electrode and a second end surface electrode; a first bus bar having a first body portion electrically connected to the first end surface electrode and a first lead portion having a first external connection terminal; a second bus bar having a second body portion electrically connected to the second end surface electrode and a second lead portion having a second external connection terminal adjacent to the first external connection terminal; a case that houses the capacitor element, a portion of the first bus bar, and a portion of the second bus bar; a sealing resin that seals the capacitor element, the first bus bar, and the second bus bar while they are housed in the case; and a vacuum-molded insulating resin member that insulates the first and second draw-out portions, wherein the inter-terminal distance between the first and second draw-out portions that face each other with the insulating resin member sandwiched therebetween is 0.8 mm or less, and the creepage distance between adjacent first and second draw-out portions is rated voltage × 0.005 mm to rated voltage × 0.007 mm.

[0008] According to the capacitor of the present invention, it is possible to reduce the parasitic inductance while ensuring the creepage distance between the pair of bus bars.

[0009] 5A is a perspective view of a capacitor unit of a capacitor according to a first embodiment; (b) is a perspective view of the capacitor unit of a capacitor according to the first embodiment from another direction; (c) is a plan view of the capacitor of FIG. 1; (d) is a perspective view of a portion of the capacitor of FIG. 1; (e) is a cross-section taken along line A-A in FIG. 3, viewed from the y-axis direction; (f) is a perspective view of an insulating member of the capacitor of FIG. 1; (g) is a cross-section taken along line B-B in FIG. 5; (h) is a perspective view of a capacitor unit of a capacitor according to a second embodiment; (i) is a plan view of the capacitor of FIG. 7; (ii) is a perspective view of a portion of the capacitor of FIG. 8; and (iii) is a view of FIG. 9, viewed from the y-axis direction.

[0010] First Embodiment A capacitor 1 according to a first embodiment will be described with reference to FIGS. 1 to 6. The drawings are illustrated so that the x-axis, y-axis, and z-axis in FIGS. 1 to 6 are in the same direction. In the following, a planar view of the capacitor 1 from the positive or negative side of the z-axis will be referred to as an "xy planar view." A planar view from the positive or negative side of the y-axis will be referred to as an "xz planar view." A planar view from the positive or negative side of the x-axis will be referred to as a "yz planar view." The same applies to FIGS. 7 to 10.

[0011] As shown in Figures 1 and 2, capacitor 1 has a plurality of metallized film capacitor elements (hereinafter referred to as capacitor elements) 10, a first bus bar 2, a second bus bar 3, an insulating member 4, a case 5, and a sealing resin 6.

[0012] 1(a) and 1(b), each capacitor element 10 has an element body 11, a first end surface electrode 12, and a second end surface electrode 13. The first end surface electrode 12 is formed by spraying a metal such as zinc onto a first end surface of the element body 11. The second end surface electrode 13 is formed by spraying a metal such as zinc onto a second end surface of the element body 11.

[0013] The element body 11 is formed by stacking two metallized films, each having aluminum vapor-deposited on a dielectric film, rolling or laminating the stacked metallized films, and pressing them into a flat shape. The element body 11 is not limited to a configuration formed by a metallized film having aluminum vapor-deposited on a dielectric film. For example, the element body 11 may be formed by a metallized film vapor-deposited with other metals, such as zinc or magnesium. The element body 11 may also be formed by a metallized film vapor-deposited with multiple of these metals. The element body 11 may also be formed by a metallized film vapor-deposited with an alloy of these metals.

[0014] The first end surface electrode 12 is used as a P-pole side, and the second end surface electrode 13 is used as an N-pole side. Alternatively, the first end surface electrode 12 may be used as an N-pole side, and the second end surface electrode 13 may be used as a P-pole side.

[0015] The first bus bar 2 and the second bus bar 3 are each formed of a conductive material such as copper. The first bus bar 2 has a main body portion 20 and a first lead portion. The first lead portion is led out from the main body portion 20. The first lead portion has a first raised portion 21 and a plurality of first external connection terminals 22. The main body portion 20 is close enough to the first end surface electrode 12 to be soldered and is electrically connected to the first end surface electrode 12. The main body portion 20 is a flat plate having a substantially rectangular outer shape in the x-y plane. The first raised portion 21 is raised in the positive z-axis direction from the end of the main body portion 20 on the positive x-axis side and has a substantially rectangular outer shape in the y-z plane. Each first external connection terminal 22 extends substantially horizontally in the positive x-axis direction from the upper end of the first raised portion 21 opposite the main body portion 20. Each of the first external connection terminals 22 has a through-portion 23 that is substantially circular in the xy plane view. The through-portion 23 fastens the first bus bar 2 to the external wiring.

[0016] The second busbar 3 has a main body portion 30 and a second lead portion. The second lead portion is led out from the main body portion 30. The second lead portion has a second raised portion 31 and a plurality of second external connection terminals 32. Similar to the first busbar 2, the main body portion 30 is close enough to the second end surface electrode 13 for soldering and is electrically connected to the second end surface electrode 13. The main body portion 30 is a flat plate having a substantially rectangular outer shape in the x-y plane. The second raised portion 31 is a flat plate having a substantially rectangular outer shape in the y-z plane, raised in the positive direction of the z-axis from the end of the main body portion 30 on the positive side of the x-axis. Each second external connection terminal 32 extends substantially horizontally in the positive direction of the x-axis from the upper end of the second raised portion 31 opposite the main body portion 30. Each second external connection terminal 32 has a substantially circular through-portion 33 in the x-y plane. The second bus bar 3 and the external wiring are fastened together through the through portion 33 .

[0017] The first bus bar 2 is used as a bus bar on the P-pole side. The second bus bar 3 is used as a bus bar on the N-pole side. Alternatively, the first bus bar 2 may be used as a bus bar on the N-pole side, and the second bus bar 3 may be used as a bus bar on the P-pole side.

[0018] An insulating member 4 is disposed between the first rising portion 21 of the first bus bar 2 and the second rising portion 31 of the second bus bar 3. This insulates the first bus bar 2 from the second bus bar 3. As shown in FIG. 5 , the insulating member 4 has a vertical insulating portion 41, a horizontal insulating portion 42, and multiple (two in this embodiment) fitting protrusions 43. The vertical insulating portion 41 is disposed between the first rising portion 21 of the first bus bar 2 and the second rising portion 31 of the second bus bar 3. The vertical insulating portion 41 has a substantially rectangular plate shape in a y-z plane view. The horizontal insulating portion 42 extends integrally in the positive direction of the x-axis from the positive end of the vertical insulating portion 41 on the z-axis side. The horizontal insulating portion 42 is disposed between the first external connection terminal 22 and the second external connection terminal 32. Each fitting protrusion 43 is fitted into a respective one of multiple fitting holes (described later) formed in the second bus bar 3 for positioning.

[0019] The insulating member (insulating resin member) 4 is formed by vacuum molding an insulating resin material. Examples of insulating resin materials include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyphenylene sulfide (PPS), syndiotactic polystyrene (SPS), polyphthalamide (PPA), polyamide / nylon 66 (PA66), and liquid crystal polymer (LCP). In particular, the insulating resin material is preferably a resin material belonging to Group I of insulating materials specified in the Japanese Industrial Standards Insulation Standard (JIS 60664).

[0020] By forming the insulating member 4 by vacuum molding a resin material belonging to Group I of insulating materials, it is possible to form an insulating member 4 with a thickness of 0.8 mm or less. Conventional resin injection molding has only been able to produce insulating member 4 as thin as about 1.0 mm at most, whereas this embodiment makes it possible to make the insulating member 4 thinner than conventional methods. Furthermore, as shown by the thin solid arrows in FIG. 4 , when the insulating member 4 is sandwiched between the first bus bar 2 and the second bus bar 3, the inter-terminal distance L between the first lead portion (first rising portion 21) and the second lead portion (second rising portion 31) can be made 0.8 mm or less.

[0021] As shown in FIGS. 3 to 5, a surrounding portion 42a is formed on the horizontal insulating portion 42. The surrounding portion 42a surrounds each second external connection terminal 32. As shown in FIGS. 3 to 5, the surrounding portion 42a has a main surface portion 42a1 and two bent portions 42a2. The main surface portion 42a1 rises in the positive direction of the z-axis along a side surface that is continuous with each of the second raised portions 31, which are the bases of each second external connection terminal 32. The two bent portions 42a2 are bent in the positive direction of the x-axis at both ends of the main surface portion 42a1 in the y-axis direction and formed integrally. The surrounding portion 42a is U-shaped in the xy plane view and is formed integrally so as to surround portions of three side surfaces of the second external connection terminal 32.

[0022] The surrounding portion 42a makes it possible to ensure a creepage distance between the adjacent first and second lead portions, as indicated by the thick solid arrows in Fig. 4. Furthermore, a creepage distance of rated voltage x 0.005 mm to rated voltage x 0.007 mm can be reliably ensured in a compact manner so as to fit within a predetermined size.

[0023] 6 , the fitting protrusions 43 are formed on the vertical insulating portion 41 during vacuum molding so that their cross sections in the xz plane form a substantially rectangular shape that protrudes in the positive direction of the x-axis. The fitting protrusions 43 fit into the multiple (two) fitting holes 34 formed in the second rising portion 31 of the second bus bar 3. This facilitates positioning of the insulating member 4 when it is inserted between the first bus bar 2 and the second bus bar 3.

[0024] Case 5 can be formed from various materials, for example, resins such as PPS or PBT, organic materials such as plastics, and inorganic materials such as ceramics. A portion of a capacitor unit having a plurality of capacitor elements 10, first bus bar 2, second bus bar 3, and insulating member 4 is housed in an interior housing section of case 5. Then, sealing resin 6 made of, for example, epoxy resin is filled into the housing space of case 5 that houses part of the capacitor unit, thereby sealing the portion of the capacitor unit.

[0025] The sealing resin 6 is not limited to epoxy resin, but may be any of various insulating materials used as sealing resins for electronic components. The sealing resin 6 is formed by being injected into the case 5 in a liquid state through an opening of the case and then curing.

[0026] According to the first embodiment, the insulating member 4 is vacuum-molded from a material belonging to Material Group I, which is one of the insulating materials specified in the insulation standards of the Japanese Industrial Standards. This makes it thinner than an injection-molded insulating resin member and stronger than insulating paper, enabling the first bus bar 2 and the second bus bar 3 to be insulated in a three-dimensional structure. This reduces parasitic inductance while ensuring a sufficient creepage distance between the first and second lead portions. Furthermore, unlike insulating paper, handling is not complicated, resulting in excellent workability.

[0027] Furthermore, the vacuum-molded insulating member 4 is used to form a surrounding portion 42a in the insulating member 4 that surrounds three side surfaces of each second external connection terminal 32. This allows a creepage distance of rated voltage × 0.005 mm to rated voltage × 0.007 mm to be secured compactly within a predetermined size between the first and second lead-out portions.

[0028] Furthermore, by fitting the fitting protrusions 43 formed on the insulating member 4 into the fitting holes 34 formed in the second bus bar 3, it is possible to easily position the insulating member 4 when inserting it between the first bus bar 2 and the second bus bar 3. In this case, compared to an insulating member made of insulating paper, a vacuum-molded insulating resin member is strong, extremely easy to handle, and has excellent workability, which contributes to improving the efficiency of the capacitor assembly process.

[0029] Second Embodiment A capacitor 1a according to a second embodiment will be described in detail with reference to Figures 7 to 10. Like the capacitor 1 according to the first embodiment, the capacitor 1a according to the second embodiment includes a plurality of metallized film capacitor elements (capacitor elements) 10, a first bus bar 2a, a second bus bar 3a, an insulating member 4a, a case 5a, and a sealing resin 6a. The configuration of the capacitor 1a according to the second embodiment differs from that of the capacitor 1 according to the first embodiment in the following respects.

[0030] In the second embodiment, the shapes of the first bus bar and the second bus bar are different from the first bus bar 2 and the second bus bar 3 of the first embodiment.

[0031] As shown in FIGS. 7 to 10 , the first busbar 2a has a main body portion 20a and a first lead portion. The first lead portion has a first rising portion 21a, a first extending portion 22a, a first falling portion 23a, and a plurality of (three in this embodiment) first external connection terminals 25a. The main body portion 20a is electrically connected to the first end surface electrode 12. The first rising portion 21a rises substantially vertically in the positive direction of the z-axis from the end of the main body portion 20a on the positive side of the x-axis. The first extending portion 22a extends substantially horizontally in the positive direction of the x-axis from the upper end of the first rising portion 21a. The first falling portion 23a falls in the negative direction of the z-axis from the end of the first extending portion 22a on the positive side of the x-axis. The first external connection terminal 25a extends substantially horizontally in the positive direction of the x-axis from the lower end of the first descending portion 23a.

[0032] As shown in FIGS. 7 to 10 , the second bus bar 3a includes a main body portion 30a and a second lead portion. The second lead portion includes a second rising portion 31a, a second extending portion 32a, a second falling portion 33a, and multiple (three in this embodiment) second external connection terminals 35a. The main body portion 30a is electrically connected to the second end surface electrode 13. The second rising portion 31a rises substantially vertically in the positive direction of the z-axis from the end of the main body portion 30a on the positive side of the x-axis. The second extending portion 32a extends substantially horizontally in the positive direction of the x-axis from the upper end of the second rising portion 31a. The second falling portion 33a falls in the negative direction of the z-axis from the end of the second extending portion 32a on the positive side of the x-axis. The second external connection terminal 35a extends substantially horizontally in the positive direction of the x-axis from the lower end of the second descending portion 33a.

[0033] Each of the first external connection terminals 25a has a through-hole 26 that is substantially circular in the xy plane. Each of the second external connection terminals 35a has a through-hole 36 that is substantially circular in the xy plane. The through-hole 26 fastens the first bus bar 2a to the external wiring. The through-hole 36 fastens the second bus bar 3a to the external wiring.

[0034] The insulating member (insulating resin member) 4a is, like the insulating member 4 of the first embodiment, for example, PP, PET, PBT, PC, PPS, SPS, PPA, PA66, or LCP. In particular, the insulating resin material is preferably a resin material belonging to Group I of insulating materials defined in the insulation standard of the Japanese Industrial Standards (JIS 60664).

[0035] The insulating member 4a is L-shaped in the x-z plane. Similar to the insulating member 4 of the first embodiment, the insulating member 4a includes a vertical insulating portion 4a1, a horizontal insulating portion 4a2, and multiple mating protrusions (not shown). The vertical insulating portion 4a1 is disposed between the first rising portion 21a of the first bus bar 2a and the second rising portion 31a of the second bus bar 3a. The vertical insulating portion 4a1 has a substantially rectangular plate shape in the y-z plane. The horizontal insulating portion 4a2 extends integrally in the positive direction of the x-axis from the positive end of the vertical insulating portion 4a1 on the z-axis side. The horizontal insulating portion 4a2 is disposed between the first extending portion 22a and the second extending portion 32a. Each mating protrusion is fitted into a corresponding one of multiple mating holes (not shown) formed in the second bus bar 3a for positioning.

[0036] Unlike the insulating member 4 of the first embodiment, the insulating member 4a of this embodiment does not have an enclosing portion. However, a horizontal insulating portion 4a2 is disposed between the first extension portion 22a and the second extension portion 32a. This ensures a creepage distance between the adjacent first and second lead portions, as shown by the thick solid arrows in FIG. 10 . Furthermore, a creepage distance of 0.005 mm to 0.007 mm of the rated voltage can be ensured compactly within a specified size.

[0037] According to the second embodiment, as in the first embodiment, the insulating member 4a is vacuum-molded from a resin material belonging to Material Group I, which is one of the insulating materials specified in the insulation standards of the Japanese Industrial Standards. This makes it thinner than an injection-molded insulating resin member and stronger than insulating paper, thereby enabling the first bus bar 2a and the second bus bar 3a to be insulated in a three-dimensional structure. This reduces parasitic inductance while ensuring a sufficient creepage distance between the first and second lead portions. Furthermore, unlike insulating paper, the insulating member 4a is not cumbersome to handle and is therefore easy to work with.

[0038] Furthermore, the insulating member 4a has a horizontal insulating portion 4a2 disposed between the first extending portion 22a and the second extending portion 32a. Therefore, even without an enclosing portion as in the first embodiment, a creepage distance of rated voltage × 0.005 mm to rated voltage × 0.007 mm can be secured between adjacent first and second extending portions in a compact manner within a predetermined size.

[0039] The present invention is not limited to the above configuration, and various design modifications are possible within the scope of the claims. The present invention is widely applicable to capacitors that have an insulating resin member disposed between a pair of bus bars and that insulates the pair of bus bars.

[0040] REFERENCE SIGNS LIST 1, 1a ... capacitor 2, 2a ... first bus bar 3, 3a ... second bus bar 4, 4a ... insulating member (insulating resin member) 5, 5a ... case 6, 6a ... sealing resin 22, 25a ... first external connection terminal 21, 21a ... first rising portion 22a ... first extending portion 23a ... first falling portion 32, 35a ... second external connection terminal 31, 31a ... second rising portion 32a ... second extending portion 33a ... second falling portion 41, 4a1 ... vertical insulating portion 42, 4a2 ... horizontal insulating portion 42a ... surrounding portion

Claims

1. A capacitor element having a first end surface electrode and a second end surface electrode; a first bus bar having a first body portion electrically connected to the first end surface electrode and a first lead portion having a first external connection terminal; a second bus bar having a second body portion electrically connected to the second end surface electrode and a second lead portion having a second external connection terminal adjacent to the first external connection terminal; a case that accommodates the capacitor element, a portion of the first bus bar, and a portion of the second bus bar; and a sealing resin that seals the capacitor element, the first bus bar, and the second bus bar while they are accommodated in the case. a vacuum-molded insulating resin member that provides insulation between the first and second draw-out portions, wherein a terminal-to-terminal distance between the first and second draw-out portions that face each other with the insulating resin member sandwiched therebetween is 0.8 mm or less, and a creepage distance between adjacent first and second draw-out portions is rated voltage×0.005 mm to rated voltage×0.007 mm.

2. The capacitor according to claim 1, wherein the insulating resin member is made of a material belonging to material group I among insulating materials defined in the insulation standard of the Japanese Industrial Standards.

3. The capacitor according to claim 1 or 2, wherein the insulating resin member has a surrounding portion surrounding a portion of a side surface of at least one of the first lead portion and the second lead portion that are adjacent to each other.

4. The capacitor according to claim 1 or 2, wherein the first draw-out portion has: a first rising portion rising approximately vertically from the first main body portion; a first extending portion extending approximately horizontally from an upper end of the first rising portion; and a first descending portion descending from an end of the first extending portion; the second draw-out portion has: a second rising portion rising approximately vertically from the second main body portion; a second extending portion extending approximately horizontally from an upper end of the second rising portion; and a second descending portion descending from an end of the second extending portion; and the insulating resin member has: a vertical insulating portion interposed between the first rising portion and the second rising portion; and a horizontal insulating portion interposed between the first extending portion and the second extending portion.

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