CAPACITOR AND METHOD FOR MANUFACTURING SAME

Abstract

A second busbar is provided that has a second electrode terminal and a second connection terminal. A first busbar is provided that has a first electrode terminal, a lateral side coupler, an overhang, and a first connection terminal. The first electrode terminal and/or the second electrode terminal has a protruding piece for connection (connecting protrusion). This protruding piece is elastically depressible in response to contact with an electrode surface of a capacitor element unit inserted from an opposite side of the lateral side coupler across a space between the first and second electrode terminals.

Claims

1. A capacitor, comprising: a capacitor element unit comprising electrode surfaces having different polarities on both end sides thereof; a first busbar and a second busbar respectively connected to the electrode surfaces; and a coating resin that covers all of the capacitor element unit and that partly covers the first and second busbars, the second busbar comprising: a second electrode terminal connected to one of the electrode surfaces; and a second connection terminal extended from the second electrode terminal, the first busbar comprising: a first electrode terminal connected to the other one of the electrode surfaces; a lateral side coupler extended from the first electrode terminal along a lateral surface of the capacitor element unit; an overhang extended from the lateral side coupler in a manner that closely overlaps the second electrode terminal; and a first connection terminal extended from the overhang, at least one of the first electrode terminal and the second electrode terminal comprising a connecting protrusion, the connecting protrusion being elastically depressible in response to contact with the electrode surface of the capacitor element unit inserted from an opposite side of the lateral side coupler across a space between the first electrode terminal and the second electrode terminal.

2. The capacitor according to claim 1, wherein the first and/or second electrode terminal is partly cut out and bent upward to form, as the connecting protrusion, a protruding piece for connection having a tongue-like shape and integral with the first and/or second electrode terminal, the protruding piece is bent in a vertically reversed, checkmark-like shape, the protruding piece, from one end on a base side toward an apex of the vertically reversed, checkmark-like shape, progressively approaches the electrode surface, the protruding piece, from the apex of the vertically reversed, checkmark-like shape toward another end, draws away from the electrode surface, and the protruding piece contacts the electrode surface at the apex of the vertically reversed, checkmark-like shape.

3. The capacitor according to claim 2, wherein the protruding piece for connection integral with the first and/or second electrode terminal is formed by being extended from an edge of a cutout hole formed in the first and/or second electrode terminal.

4. The capacitor according to claim 3, wherein the first busbar is connected to the electrode surface on a lower end side of the capacitor element unit, and the protruding piece for connection is formed on the first electrode terminal on a side where the lateral side coupler is disposed.

5. The capacitor according to claim 3, wherein the protruding piece for connection is extended from the edge of the cutout hole of the first electrode terminal at or near a position most proximate to the lateral side coupler on a whole circumference in a direction away from the lateral side coupler.

6. The capacitor according to claim 4, wherein the first and/or second electrode terminal has a plurality of the protruding pieces for connection integrally formed, and all of the plurality of protruding pieces for connection are extended from the edges of the cutout holes in parallel to each other in a direction away from the lateral side coupler.

7. The capacitor according to claim 1, wherein an insulating member in the form of a sheet is interposed between the overhang of the first busbar and the second electrode terminal of the second busbar that closely overlaps the overhang.

8. A manufacturing method for the capacitor according to claim 1, comprising: a first step of setting the first busbar on a soldering jig; a second step of inserting the second busbar from a lateral side, with the second electrode terminal being positioned to follow a lower surface of the overhang of the first busbar; and a third step of inserting the capacitor element unit from a lateral side into a space between the first electrode terminal and the second electrode terminal, the third step further comprising: inviting at least one of the electrode surfaces to make sliding contact with the connecting protrusion to elastically depress the connecting protrusion during the insertion of the capacitor element unit; and pushing the connecting protrusion against the at least one of the electrode surfaces using an elastic restoring force of the protrusion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG. 1 is a cross-sectional view of a capacitor according to an example of this invention.

[0065] FIG. 2 is a perspective view of a capacitor element unit in the capacitor according to the example of this invention.

[0066] FIG. 3 is a perspective view of a first busbar in the capacitor according to the example of this invention.

[0067] FIG. 4 is a perspective view of a cutout hole and a protruding piece for connection in the capacitor according to the example of this invention; an example of the connecting protrusion disclosed herein.

[0068] FIG. 5 is a perspective view of a second busbar in the capacitor according to the example of this invention.

[0069] FIG. 6 is a perspective view that illustrates assembling steps (first and second busbars) in the capacitor according to the example of this invention.

[0070] FIG. 7 is a perspective view that illustrate assembling steps (first and second busbars) in the capacitor according to the example of this invention.

[0071] FIG. 8a is a drawing of an assembling step in the capacitor according to the example of this invention, illustrating how a protruding piece for connection acts in response to the insertion of a capacitor element unit.

[0072] FIG. 8b is a drawing of an assembling step in the capacitor according to the example of this invention, illustrating how the protruding piece for connection acts in response to the insertion of the capacitor element unit.

[0073] FIG. 8c is a drawing of an assembling step in the capacitor according to the example of this invention, illustrating how the protruding piece for connection acts in response to the insertion of the capacitor element unit.

[0074] FIG. 9a illustrates a working step of the known art (1).

[0075] FIG. 9b illustrates a working step of the known art (1).

[0076] FIG. 10a illustrates a working step of the known art (2).

[0077] FIG. 10b illustrates a working step of the known art (2).

[0078] FIG. 10c illustrates a working step of the known art (2).

[0079] FIG. 10d illustrates a working step of the known art (2).

[0080] FIG. 11 is a perspective view of a cutout hole and a protruding piece for connection of the known art.

[0081] FIG. 12a illustrates a working step of the known art (3).

[0082] FIG. 12b illustrates a working step of the known art (3).

[0083] FIG. 12c illustrates a working step of the known art (3).

[0084] FIG. 13 is a cross-sectional view that illustrates a problem with the known art.

DESCRIPTION OF EMBODIMENTS

[0085] The capacitor disclosed herein is more specifically described below based on specific examples of this invention.

[0086] In FIGS. 1 to 7 and 8a to 8c are illustrated a capacitor element 1, a capacitor element unit U, a first electrode surface 2A on a lower end side of the capacitor element unit U, a second electrode surface 2B on an upper end side of the capacitor element unit U, a first busbar B1, a second busbar B2, and an exterior resin (coating resin). The capacitor element 1 may be, for example, a film capacitor in which a dielectric film and a metallic film (electrode) are alternately stacked in layers or a film capacitor wound around with layers of a dielectric film having at least one metallized surface.

[0087] As illustrated in FIGS. 2 and 7, the capacitor element unit U includes the capacitor elements 1 that are arranged in a matrix shape with three rows and three columns. The matrix of three rows and three columns is just an example. The matrix may optionally consist of “m” number of columns and “n number of rows where the “m” and the “n” are each an integer greater than 1 (m=1, 2, . . . , n=1, 2, . . . ). The “m”דn” number of capacitor elements 1 are orderly and closely arranged in axially parallel to one another and have a rectangular or square shape on the whole in plan view.

[0088] As illustrated in FIG. 1, the capacitor elements 1 each have a first electrode surface 1a on an axially lower end side and further have a second electrode surface 1b on an axially upper end side. The first electrode surface la and the second electrode surface 1b naturally have polarities that differ from each other. In the capacitor element U having nine capacitor elements 1 arranged in three rows and three columns, the nine first electrode surfaces 1a may be collectively referred to as first electrode surface 2A, while the nine second electrode surfaces 1b may be collectively referred to as second electrode surface 2B.

[0089] As illustrated in FIG. 3, the first busbar B1 has a first electrode terminal 11, a lateral side coupler 12, an overhang 13, and a first connection terminal 14. The first electrode terminal 11 is connectable to the first electrode surface 2A on the lower end side of the capacitor element unit U. The lateral side coupler 12 is extended from the first electrode terminal 11 along a lateral surface of the capacitor element unit U. The overhang 13 is extended from the lateral side coupler 12 in a manner that vertically closely overlaps the second electrode terminal 21 of the second busbar B2. The first connection terminal 14 is extended from the overhang 13.

[0090] As illustrated in FIG. 5, the second busbar B2 has a second electrode terminal 21 and a second connection terminal 24. The second electrode terminal 21 is connectable to the second electrode surface 2B on the upper end side of the capacitor element unit U. The second connection terminal 24 is extended upward from the second electrode terminal 21.

[0091] There are certain tolerances among the vertical widths (axial lengths) of the nine capacitor elements 1 in the capacitor element unit U. A protruding piece 11a for connecting purpose; an example of the connecting protrusion, may serve to absorb such tolerances, which is described below.

[0092] As illustrated in FIG. 4, the first electrode terminal 11 of the first busbar B1 is partly cut out in a tongue-like shape and bent upward to form the protruding piece 11a for connecting purpose. The protruding pieces 11a are thus formed integral with this electrode terminal. Specifically, the protruding pieces 11a are each extended from an edge of a cutout hole 11b when these holes are formed in the first electrode terminal 11. As is clear from FIGS. 2 and 3 compared with each other, of the protruding pieces 11a for connecting purpose, two protruding pieces are formed for each of the capacitor elements 1 arranged in the 3×3 matrix shape and are spaced at equal intervals. Likewise, of the cutout holes 11b used to form the protruding pieces 11a, two cutout holes are formed for each of the capacitor elements 1 arranged in the 3×3 matrix shape. In any other portions but the peripheral edge of the first electrode terminal 11, the cutout holes 11b are each shaped with a closed curve. On the other hand, some of the cutout holes 11b at the peripheral edge of the first electrode terminal 11 are each shaped with an open curve and are thus open and continuous to the outer space.

[0093] As illustrated in FIG. 3, the protruding pieces 11a for connecting purpose; two for a respective one of the capacitor elements 1, are each extended from the edge of the cutout hole 11b in the first electrode terminal 11 at or near a position most proximate to the lateral side coupler 12 on the whole circumference of the cutout hole. The direction of extension of the protruding piece 11a for connecting purpose coincides with a direction away from the lateral side coupler 12 (opposite to the direction of insertion of the capacitor element unit U), i.e., all of the protruding pieces 11a for connecting purpose are parallel to one another in plan view.

[0094] As illustrated in FIG. 4, the protruding pieces 11a for connecting purpose are bent in a vertically reversed, checkmark-like shape. The protruding piece 11a inclines obliquely upward from its base part at the edge of the cutout hole 11b toward an apex of the vertically reversed, checkmark-like shape, approaching the first electrode surface 2A of the capacitor element unit U. The protruding piece 11a then inclines obliquely downward toward its free end side from the apex of the vertically reversed, checkmark-like shape, drawing away from the first electrode surface 2A. The protruding piece 11a contacts the first electrode surface 2A at the apex of the vertically reversed, checkmark-like shape. The free end of the protruding piece 11a is substantially flush in height with the cutout hole 11b.

[0095] As illustrated in FIG. 5, the second busbar B2 has a second electrode terminal 21 in the form of a flat plate and a second connection terminal 24 standing upward from the second electrode terminal 21. The second electrode terminal 21 also has protruding pieces for connection; protruding pieces 21a having a tongue-like shape and formed integral with the second 6electrode terminal 21. Specifically, the protruding pieces 21a are each extended from an edge of a cutout hole 21b when these holes are formed in the second electrode terminal 21. Of the protruding pieces 21a for connecting purpose, two protruding pieces 21a are formed for each of the capacitor elements 1 arranged in the 3×3 matrix shape and are spaced at equal intervals. The cutout holes 21b are also formed likewise. In any other portions but the peripheral edge of the second electrode terminal 21, the cutout holes 21b are each shaped with a closed curve. On the other hand, some of the cutout holes 21b at the peripheral edge of the second electrode terminal 21 are each shaped with an open curve and are thus open and continuous to the outer space.

[0096] In some of the protruding pieces 21a for connecting purpose of the second busbar B2, their tongue-shaped tips may not be uniformly directed, unlike the protruding pieces 11a of the first busbar B1. Some of the protruding pieces 21a are extended likewise in the same direction as the direction of insertion. The other protruding pieces 21a, on the other hand, may be extended in the opposite direction of insertion or extended in a direction perpendicular to the direction of insertion and then further extended rightward or leftward. These protruding pieces being thus differently directed may certainly improve a soldering strength between the capacity element unit U and the second electrode terminal 21.

[0097] The protruding pieces 21a for connecting purpose of the second electrode terminal 21 are not formed in such a vertically reversed checkmark as the protruding piece 11a of the first electrode terminal 11 but are formed flush with the plane of the second electrode terminal 21. In order to adhere the first and second electrode terminals 11 and 21 under pressure to the first and second electrode surfaces 2A and 2B of the capacitor element unit U, the first electrode terminal 11 alone may be required to have the protruding pieces shaped like a reversed checkmark.

[0098] Referring to FIG. 6 and FIGS. 3 and 5 viewed for comparison, the first electrode terminal 11 of the first busbar B1 and the second electrode terminal 21 of the second busbar B2 are substantially equal in size. The overhang 13 of the first busbar B1 is significantly smaller than the first electrode terminal 11 and the second electrode terminal.

[0099] As illustrated in FIGS. 1, 6 and 7, the overhang 13 of the first busbar B1 is formed in a manner that vertically closely overlaps the second electrode terminal 21 of the second busbar B2 and that extends in parallel to this electrode terminal. An insulating member 31 in the form of a sheet is further provided that has a horizontal portion and a vertical portion. The horizontal portion is interposed between the overhang 13 and the second electrode terminal 21 that vertically closely overlaps the overhang. The vertical portion is fitted in a vertically small space between the first connection terminal 14 and the second connection terminal 24 facing each other in proximity.

[0100] FIG. 1 includes structural features not illustrated in FIGS. 6 and 7. In this drawing, the first connection terminal 14 and the second connection terminal 24 are disposed at positions near the center of the capacitor, which differ from the examples illustrated in FIGS. 6 and 7 in which these terminals have been displaced. FIG. 1 illustrates the structurally simplified first and second connection terminals 14 and 24, as compared with FIGS. 6 and 7. These minor changes are solely intended to help the readers to easily understand the conceptual elements of this invention and should not be construed as having any significant impact on the true nature of this invention.

[0101] Next is described how to mount the first busbar B1, second busbar B2 and capacitor element unit U to a soldering jig (not illustrated in the drawings).

[0102] 1] First, the sheet-like insulating member 31 is bonded to the lower surface of the overhang 13 and to the outer surface of the first connection terminal 14 of the first busbar B1 (see FIG. 3). Then, the first busbar B1 with the sheet-like insulating member 31 is set on the soldering tool (first step). [0103] 2] In the first busbar B1 illustrated in FIG. 3, the second busbar B2 illustrated in FIG. 5 is laterally moved and inserted into a space 40 through its opening 40a on one side. The space 40 is formed by the lower-end first electrode terminal 11 horizontally disposed, the lateral side coupler 12 vertically disposed, and the insulating member 31 bonded to the upper-end overhang (second step). FIG. 6 illustrates the result of this step. The second busbar B2 is inserted into this space, with the second electrode terminal 21 being disposed along the lower surface of the overhang 13. As a result, the second electrode terminal 21 is moved toward and located near the lower surface of the overhang 13, and the horizontal portion of the sheet-like insulating member 31 is interposed between this electrode terminal and overhang. Further, the second connection terminal 24 is moved toward and located near the first connection terminal 14, and the vertical portion of the sheet-like insulating member 31 is interposed between these connection terminals.

[0104] Next, the capacitor element unit U is laterally moved and inserted into the space 40 through its opening 40a on one side (third step). FIG. 7 illustrates the result of this step.

[0105] As illustrated in FIGS. 8a to 8c, the capacitor element unit U, after being inserted in the space 40 through the opening 40a, moves into the back of the space 40 (right side on FIGS. 8a to 8c) while its upper-end corner 3B and lower-end corner 3A on the lateral surface ahead in the direction of movement (see FIG. 1) are making sliding contact with, respectively, the lower surface of the second electrode terminal 21 of the second busbar B2 and the upper surface of the first electrode terminal 11 of the first busbar B1.

[0106] In the known art, the elastic and straight, tongue-shaped protruding piece 11a′ for connecting purpose formed integral with the first electrode terminal 11 of the first busbar B1 may be likely to act against the insertion of the capacitor element unit U. When the lower-end corner 3A of the capacitor element unit U contacts the protruding piece 11a′ for connecting purpose, the protruding piece 11a′ may block any further movement of the capacitor element unit into the space 40. In case the capacitor element unit is then forced further into the space, the protruding piece 11a′ may break, degrading the product quality of the capacitor.

[0107] In the example of this invention, the tongue-shaped protruding piece 11a for connecting purpose has elasticity and is formed in a vertically reversed checkmark-like shape. The free end side of the protruding piece 11a is substantially flush in height with or lower than the first electrode terminal 11. Thus, the lower-end corner 3A of the capacitor element unit U may be guided from the free end side of the protruding piece 11a onto the inclined upper surface of the protruding piece 11a. During this guiding movement, the protruding piece 11a may be elastically depressed.

[0108] As the capacitor element unit U that passed the apex of the checkmark-like shape moves further into the back of the space, the protruding piece 11a for connecting purpose is pushed downward and thereby almost flattened by the lower surface of the capacitor element unit U. The elastic restoring force of the protruding piece 11a may be accordingly increased to be strong enough to elastically press, from below, the first electrode surface 2A of the capacitor element unit U in the upper direction. As a result, the second electrode surface 2B of the capacitor element unit U may be elastically pushed against the lower surface of the second electrode terminal 21 of the second busbar B2.

[0109] In the capacitor element unit U, the capacitor elements are each pushed by two elastic, tongue-shaped protruding pieces 11a for connecting purpose. Thus, the whole capacitor element unit U is pressed by 18 protruding pieces 11a for connecting purpose that are spaced at equal intervals (in one example). The capacitor element unit U may be inserted in a stable posture into the space 40 formed by the first and second busbars B1 and B2.

[0110] The second electrode surface 2B on the upper end side of the capacitor element unit U contacts the whole second electrode terminal 21 of the second busbar B2 under a substantially equal pressing force and may be accordingly soldered well to the second electrode terminal 21 at positions of the protruding pieces 21a formed at the cutout holes 21b of the second electrode terminal B2. Further, the first electrode surfaces 1a of the capacitor elements 1 in the capacitor element unit U are pressed by the reversed checkmark-like, tongue-shaped the protruding pieces 11a. This pressing action may favorably absorb tolerances, if any, among the vertical widths (axial lengths) of the capacitor elements 1. Thus, the first electrode surfaces 1a of all of the capacitor elements 1 may be powerfully pressed by the protruding pieces 11a, and the first electrode surface 21A may be accordingly soldered well to the first electrode terminal 11.

[0111] The protruding pieces 21a for connecting purpose formed on the second electrode terminal 21 of the second busbar B2 may not be uniformly directed, unlike the protruding pieces 11a for connecting purpose formed on the first electrode terminal 11 of the first busbar B. The directions of the protruding pieces 21a are thus variable, because current paths from these protruding pieces to the second connection terminal 24 may differ from one another and are redesigned to reduce to the minimum.

[0112] On the contrary, the protruding pieces 11a for connecting purpose of the first busbar B1 are all disposed in parallel to one another, and the base part of each protruding piece 11a is located at or near a position most proximate to the lateral side coupler 12 on the whole circumference of the cutout hole 11b, because electric current from the protruding pieces 11 for connecting purpose is once directed toward the lateral side coupler 12 on the first electrode terminal 11 and is then directed to flow toward the first connection terminal 14 through the lateral side coupler 12 and the overhang 13. Thus, the current path length from a respective one of the protruding pieces 11a to the first connection terminal 14 may be reduced to the minimum. As a result, the ESL (equivalent series inductance) and the ESR (equivalent series resistance) of the first busbar may be favorably lowered.

[0113] In the example described above, the first electrode terminal 11 is provided with the reverse checkmark-like, protruding pieces 11a for connecting purpose, which is an example of the connecting protrusion disclosed herein. Instead, these reverse checkmark-like protruding pieces may be formed on the second electrode terminal 21 of the second busbar B2, or may otherwise be formed on both of the upper and lower busbars B1 and B2 after their degrees of protrusion are adjusted. The reverse checkmark-like, protruding pieces for connection may be at least formed on either one of the first electrode terminal 11 of the first busbar B1 or the second electrode terminal 21 of the second busbar B2.

[0114] In the example was described the caseless capacitor coated with the exterior resin (coating resin) 30 on its outermost side. Instead, a case-molded capacitor may be employed in which a case containing the whole capacitor is injected with a coating resin.

[0115] In the first busbar and/or the second busbar, the connection terminal and the electrode terminal may be separate components and coupled to each other with rivets or by welding.

[0116] In the example described above, the reverse checkmark-like, tongue-shaped protruding piece for connection was presented as a suitable example of the elastically depressible “connecting protrusion”. The connecting protrusion disclosed herein is not necessarily limited to such a protruding piece but is selectable from any other suitable examples variously modified within the scope of this invention.

[0117] For example, the protruding piece for connection is not necessarily formed in such a cantilever-like form as described herein (protruding piece having a free end on one side) but may be formed with closed ends on both sides (both ends being connected to the hole edge). The protruding piece with closed ends may be rendered elastically depressible without any difficulty.

INDUSTRIAL APPLICABILITY

[0118] In a capacitor including a capacitor element unit surrounded by first and second busbars arranged in cross section in a substantially horizontally flipped, rectangular C-like shape and also including elastic protruding pieces for absorption of tolerances among the vertical widths of capacitor elements, this invention provides an advantageous technology for better assembling workability that enables smooth and easy insertion of the capacitor element unit without interference of the protruding pieces and without major changes of a soldering jig.

REFERENCE SIGNS LIST

[0119] 1 capacitor element [0120] 1a first electrode surface of capacitor element [0121] 1b second electrode surface of capacitor element [0122] 2A first electrode surface of capacitor element unit [0123] 2b second electrode surface of capacitor element unit [0124] 11 first electrode terminal [0125] 11a protruding piece for connection (connecting protrusion) [0126] 11b cutout hole [0127] 12 lateral side coupler [0128] 13 overhang [0129] 14 first connection terminal [0130] 21 second electrode terminal [0131] 24 second connection terminal [0132] 30 exterior resin (coating resin) [0133] 31 sheet-like insulating member [0134] B1 first busbar [0135] B2 second busbar [0136] U capacitor element unit