Film capacitor

Abstract

The objective is to provide a film capacitor that can ensure high heat dissipation. [Solution] The film capacitor 1 of the present invention comprises a plurality of capacitor elements 10, a case 20 for housing the capacitor elements 10, and a filling resin 50 filled inside the case 20, wherein the case 20 comprises a bottom wall 24 having a circular or arc-shaped outer edge 21 and a circular or arc-shaped inner edge 22 on the central side of the circular or arc-shaped outer edge 21, an outer wall 25 erected from the outer edge 21, and an inner wall 26 erected from the inner edge 22, wherein the electrodes 11a and 11b of the capacitor elements 10 are arranged radially inward and outward within the case 20, and the capacitor elements 10 are housed in the case 20 in a circumferential arrangement.

Description

Technical Field

[0005] , , ,

[0001] The present invention relates to a film capacitor.

Background Art

[0002] In recent years, the introduction of electric vehicles and hybrid electric vehicles has been progressing in the automotive industry.

[0003] Since the motors used in these electric vehicles operate at a high voltage of several hundred volts, film capacitors having high withstand voltage and low loss electrical characteristics have come to be used as the capacitors used in relation to the motors. As the shape of such a film capacitor, for example, a capacitor in which a plurality of capacitor elements are housed in a circular case is known (Patent Document 1). The capacitor described in Patent Document 1 is filled with resin from above inside the case in which the capacitor elements are housed. The resin is filled for the purpose of protecting the capacitor elements from moisture and impact.

Prior Art Documents

Patent Documents

[0004]

Patent Document Ⅰ

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since heat is generated in the capacitor element during operation, it is necessary to discharge the generated heat to the outside. Generally, a film capacitor is said to have good heat conduction in the direction between electrodes. In the capacitor of Patent Document 1, the electrodes of the capacitor element are arranged on the upper and lower surfaces of the case, and the upper surface of the capacitor element is covered with resin but is not close to the case. Therefore, the electrode on the upper surface side of the capacitor element cannot dissipate heat through the case, and there is room for improvement in heat dissipation.

[0006] This invention has been made in view of the above problems, and aims to provide a film capacitor that can ensure high heat dissipation. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides the following means.

[0008] [1] A film capacitor comprising a plurality of capacitor elements, a case for housing the capacitor elements, and a filling resin filled inside the case, The case comprises a bottom wall having a circular or arc-shaped outer edge and a circular or arc-shaped inner edge on the central side of the circular or arc-shaped outer edge, an outer wall erected from the outer edge, and an inner wall erected from the inner edge. The electrodes of the capacitor element are arranged radially inward and outward within the case, and the capacitor element is housed in a circumferential arrangement within the case.

[0009] According to this invention, since the case is circular or arc-shaped, it is easy to mount the film capacitor inside the wheel of an automobile. Because the electrodes of the capacitor element are arranged radially inward and outward, the electrodes of the capacitor element and the case are in close proximity, making it easy to dissipate heat from the electrodes to the outside through the case, thus ensuring high heat dissipation performance.

[0010] [2] Flat portions are formed on the inner side of the inner wall and on the inner side of the outer wall of the case. The capacitor element is arranged facing the planar portion. According to this invention, although the inner and outer walls of the case are circular or arc-shaped, a flat surface is formed, allowing the entire surface of the electrodes of the capacitor element on the flat surface to be brought close to the flat surface of the case, thereby improving heat dissipation.

[0011] [3] Each capacitor element is housed in a small case made of an insulating material, The aforementioned small case is housed in the aforementioned case. According to this invention, since each capacitor element is housed in a small case, high insulation can be ensured.

[0012] [4] The filling resin is filled into the small case in which the capacitor element is housed. According to this invention, the capacitor element inside the small case can be fixed by filling the small case with a filling resin.

[0013] [5] Crush ribs are provided on the outer surface of the small case on both electrode sides, The small case is press-fitted with respect to the case, with the crush ribs in contact with the outer wall and the inner wall of the case. According to this invention, since crush ribs are provided on the small case, the small case can be securely fixed in a predetermined position within the case. [Effects of the Invention]

[0014] This allows us to provide a film capacitor that can ensure high heat dissipation. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view of a film capacitor, which is one embodiment of the present invention. [Figure 2] This is an overall diagram of a film capacitor, which is one embodiment of the present invention. [Figure 3] Figure 1 is a perspective view of the case that makes up the film capacitor. [Figure 4] Figure 1 is a top view of a film capacitor. [Figure 5A] This figure shows the capacitor element before it is housed in the resin case. [Figure 5B] This diagram shows the state after the capacitor element has been housed in a resin case. [Figure 6]It is a cross-sectional view of the A-A line of the film capacitor. [Figure 7] It is a diagram showing the first bus bar. [Figure 8] It is a diagram showing the second bus bar. [Figure 9] It is a diagram showing the insulating member.

Mode for Carrying Out the Invention

[0016] In the following description, the opening direction of the case 20 in FIG. 1 is referred to as "up".

[0017] (Film Capacitor) The film capacitor of the present invention is used in an electronic circuit of an electronic device, and is particularly preferably used in an electronic circuit related to an electric vehicle or a hybrid electric vehicle.

[0018] The film capacitor 1 of the present embodiment includes a capacitor element 10, a case 20 that houses the capacitor element 10, and a filling resin 50 that is filled in the case as basic components.

[0019] (Capacitor Element) The capacitor element 10 of the present embodiment has electrodes 11a and 11b on both side surfaces.

[0020] The capacitor element 10 is formed by laminating and winding two metallized films obtained by vapor-depositing aluminum on a dielectric film, and applying a metallization process of spraying zinc on both end faces, so that an electrode 11a is formed on one side surface and an electrode 11b is formed on the other side surface.

[0021] As the dielectric film, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), etc. can be used.

[0022] Lead wires 12a and 12b are attached to each electrode 11a and 11b of the capacitor element by soldering or welding. The lead wires 12a and 12b are attached parallel to the electrodes 11a and 11b of the capacitor element 10 and pointing upward. When the lead wires 12a and 12b are attached to each electrode 11a and 11b of the capacitor element by welding, approximately half of the total length of the lead wires 12a and 12b is inserted into the thickness of the electrodes 11a and 11b of the capacitor element 10 and fixed in place.

[0023] As shown in Figure 5A, the capacitor element 10 of this embodiment has the shape of a roughly rectangular prism with rounded corners.

[0024] Multiple capacitor elements 10 are housed within the case 20. As shown in Figure 1, in this embodiment, nine capacitor elements 10 are housed within the case 20.

[0025] In this embodiment, each capacitor element 10 is housed in a small case 40 made of an insulating material, and the entire small case 40 is housed inside the case 20.

[0026] (case) The case 20 is a component that houses multiple capacitor elements 10 and the busbar unit 30 described later.

[0027] Case 20 is circular or arc-shaped, with a cylindrical cavity in the central part. In this embodiment, the arc-shaped case 20 shown in Figure 3 will be described. The arc-shaped case 20 in this embodiment is a semicircle with a central angle of 180°, and two of these arc-shaped cases 20 are combined to form a circle.

[0028] The case 20 of this embodiment includes a bottom wall 24, an outer wall 25, an inner wall 26, and an end side wall 27.

[0029] The bottom wall 24 has an arc-shaped outer edge 21 and an arc-shaped inner edge 22 on the center side of the arc of the outer edge 21. The outer wall 25 is erected upward from the outer edge 21 of the bottom wall 24. The inner wall 26 is erected upward from the inner edge 22 of the bottom wall 24.

[0030] The end side walls 27 are erected upward from the end edge 23 that connects the outer edge 21 and inner edge 22 at both ends of the bottom wall 24, and are joined to the outer wall 25 and the inner wall 26.

[0031] The top of case 20 is open, and the capacitor element 10 is housed through the open top surface.

[0032] The material of case 20 is not particularly limited, but examples include metal or resin. From the viewpoint of heat dissipation, it is preferable to use metal.

[0033] The manufacturing method for case 20 is not particularly limited, but if it is made of metal, it can be manufactured by methods such as casting, cutting, or forging.

[0034] As shown in Figure 3, multiple protrusions 28 are provided on the inner surface of the outer wall 25 and the inner surface of the inner wall 26. The protrusions 28 are solid.

[0035] The protrusions 28 are provided at equal intervals so as to face the outer wall 25 and the inner wall 26. All of the protrusions 28 are formed to be the same size.

[0036] The inner surfaces of the projections 28 provided on the inner surface of the outer wall 25 and the inner surface of the inner wall 26 are flat. In the following description, these flat surfaces of the projections 28 will be referred to as the flat portion 29.

[0037] (Small case) As shown in Figure 5A, the small case 40 is formed in the shape of a rectangular prism box with an open top.

[0038] The material of the small case 40 is not particularly limited as long as it has insulating properties, but an insulating resin is preferred, for example, PPS resin is used.

[0039] The capacitor element 10 is housed in a small case 40 with its electrodes 11a and 11b facing sideways.

[0040] The small case 40 is sized to accommodate the capacitor element 10 with almost no gaps. The electrodes 11a and 11b of the capacitor element 10 housed in the small case 40 are in close proximity to the electrode-facing wall 41 of the small case 40.

[0041] The thickness of the small case 40 is not limited, but it is preferable that the thickness of the electrode-facing wall 41 ensures insulation between the electrodes 11a and 11b of the capacitor element and the material outside the small case 40, while also ensuring thermal conductivity.

[0042] The small case 40, which houses the capacitor element 10, is filled with a filler resin 50.

[0043] As shown in Figure 5B, crush ribs 42 are provided on the outer surface of the electrode-facing wall 41 of the small case 40. In this embodiment, the crush ribs 42 are formed as protrusions extending vertically in the center of the electrode-facing wall 41.

[0044] The small case 40 housing the capacitor element 10 is positioned between a pair of protrusions 28 provided on the inside of the case 20.

[0045] When the small case 40 is housed in the case 20, the crush ribs 42 of the small case 40 are press-fitted in contact with the outer wall 25 and inner wall 26 of the case 20. When the small case 40 is housed in the case 20, the outer surface of the electrode-facing wall 41 is in close proximity to the flat portion 29 of the projection 28.

[0046] As shown in Figure 4, the capacitor elements 10 have electrodes 11a and 11b positioned radially inward and outward within the case 20, and the capacitor elements 10 are arranged at equal intervals in the circumferential direction within the case 20. The capacitor elements 10 are positioned facing each other in close proximity to the flat portion 29 of the projection 28.

[0047] (Bus bar unit) As shown in Figure 6, with the capacitor element 10 housed in the case 20, the first busbar 31, the insulating member 33, and the second busbar 32 are mounted on top of each other from above.

[0048] In the following description, the first busbar 31, the second busbar 32, and the insulating member 33 together will be referred to as the busbar unit 30.

[0049] Figure 7 shows the first busbar 31, Figure 8 shows the second busbar 32, and Figure 9 shows the insulating member.

[0050] The first busbar 31, the second busbar 32, and the insulating member 33 each have arc-shaped main body portions 310, 320, and 330 that are slightly smaller than the opening of the case 20. The main body portion 330 of the insulating member 33 is formed to be larger than the main body portion 310 of the first busbar 31 and the main body portion 320 of the second busbar 32, ensuring insulation between the first busbar 31 and the second busbar 32.

[0051] The first busbar 31, the second busbar 32, and the insulating member 33 have holes formed in them at positions corresponding to the lead wires 12a and 12b that extend upward from the electrodes 11a and 11b of the capacitor element 10.

[0052] The first bus bar 31 has an outer hole 31a on the outer wall 25 side with a diameter larger than the lead wire 12a, and an inner hole 31b on the inner wall 26 side with a diameter approximately the same as the lead wire 12b.

[0053] The second bus bar 32 has an outer hole 32a on the outer wall 25 side that is approximately the same diameter as the lead wire 12a, and a semicircular inner hole 32b on the inner wall 26 side that is larger in diameter than the lead wire 12b.

[0054] The insulating member 33 has holes 33a that are slightly larger than the lead wires at positions corresponding to each lead wire 12a and 12b. These holes 33a are smaller than the large outer holes 31a and inner holes 32b provided in the first bus bar 31 and the second bus bar 32, and larger than the small inner holes 31b and outer holes 32a.

[0055] The electrode 11a of the capacitor element 10 located on the outer wall 25 side of case 20 is soldered to the outer hole 32a of the second bus bar 32 by a lead wire 12a, thereby electrically connecting it to the second bus bar 32. This lead wire 12a does not come into contact with the outer hole 31a of the first bus bar 31.

[0056] Furthermore, the electrode 11b of the capacitor element 10 located on the inner wall 26 side is soldered to the inner hole 31b of the first bus bar 31 by a lead wire 12b, and is electrically connected to the first bus bar 31. This lead wire 12b does not come into contact with the inner hole 32b of the second bus bar 32.

[0057] As shown in Figure 1, the busbar unit 30 has external connection points 34 at three locations: the left end of the case, the center of the case, and the right end of the case.

[0058] As shown in Figures 7-9, each connection portion 34 has a first busbar 31, a second busbar 32, and an insulating member 33, all of which have raised portions 341, 342, and 343 bent upward from the main body portions 310, 320, and 330 near the outer wall of the case 20. Horizontal portions 344, 345, and 346 are formed from the upper edges of the raised portions 341, 342, and 343 that exceed the height of the outer wall of the case 20, extending horizontally outward from the case 20.

[0059] The horizontal section 344 of the uppermost first busbar 31 is the shortest, the horizontal section 345 of the lowermost second busbar 32 is the longest, and the horizontal section 346 of the insulating member 33 is of an intermediate length.

[0060] As a result, at the connection point 34, the horizontal sections 344 and 345 of both the first busbar 31 and the second busbar 32 can be seen from above.

[0061] Furthermore, the width of the rising portion 343 and the horizontal portion 346 of the insulating member 33 is larger than the width of the rising portions 341, 342 and the horizontal portions 344, 345 of the first and second busbars 31 and 32.

[0062] This ensures sufficient creepage distance between the first busbar 31a and the second busbar 32, resulting in adequate insulation performance.

[0063] As described above, the case 20, which houses the capacitor element 10 and to which the busbar unit 30 is attached, is filled with a filler resin 50. For example, epoxy resin can be used as the filler resin 50. As shown in Figure 2, the filler resin 50 is filled in an amount sufficient to cover the entire inside of the case 20.

[0064] (effect) In this embodiment, the electrodes 11a and 11b of the capacitor element 10 are housed in the radial direction inward and outward within the case 20, so that the electrodes 11a and 11b of the capacitor element 10 are in close proximity to the outer wall 25 or inner wall 26 of the case 20. As a result, the heat generated from the capacitor element 10 is easily dissipated to the outside through the electrodes 11a and 11b and the case 20, ensuring high heat dissipation performance. Furthermore, in this embodiment, the capacitor element 10 is housed in the case 20 with the entire surfaces of electrodes 11a and 11b in close proximity to the flat portion 29 of the projection 28. This facilitates heat transfer from electrodes 11a and 11b to the flat portion 29, thereby ensuring particularly high heat dissipation.

[0065] Furthermore, in this embodiment, since the protrusions 28 of the case 20 are solid, heat is easily transferred through the protrusions 28, thereby ensuring even higher heat dissipation.

[0066] Furthermore, in this embodiment, by housing the capacitor element 10 in a small case 40, insulation between the electrodes 11a and 11b of the capacitor element and the material outside the small case 40 can be ensured at the electrode-facing wall 41, and thermal conductivity can also be ensured.

[0067] Furthermore, in this embodiment, when the small case 40 containing the capacitor element 10 is placed in the case 20, the crush ribs 42 of the small case 40 are pressed into contact with the outer wall 25 and inner wall 26 of the case 20, so that the small case 40 can be securely fixed in a predetermined position inside the case 20 by the crush ribs 42.

[0068] (Other aspects) In the above embodiment, aluminum is deposited on a dielectric film, but the invention is not limited to this, and metals such as zinc and magnesium may be deposited. Alternatively, multiple metals from among these may be deposited, or an alloy made of these metals may be deposited.

[0069] Furthermore, although zinc is used for the metallizing treatment in the above embodiment, the invention is not limited to zinc, and other metals such as tin may also be used.

[0070] Furthermore, although the above embodiment describes a capacitor element 10 with an oval-shaped end face, the shape of the end face of the capacitor element 10 is not limited to this, and may be circular, for example. The small case 40 only needs to be able to accommodate the capacitor element 10. For example, if the capacitor element 10 is cylindrical (the end face shape of the capacitor element 10 is circular), the small case 40 may be cylindrical.

[0071] Furthermore, although the above embodiment described a case 20 with a circular arc shape and a central angle of 180°, case 20 is not limited to a circular arc shape, and may also be a circular shape with a cylindrical cavity in the center.

[0072] Furthermore, although the above embodiment described a case in which the capacitor elements 10 are housed in a small case 40, each capacitor element 10 may not be housed in a small case 40 but directly in the case 20.

[0073] Furthermore, although the above embodiment described a case in which nine capacitor elements 10 are housed in the case 20, the number of each capacitor element 10 is not limited.

[0074] Furthermore, although the above embodiment described a case in which each capacitor element 10 is housed at equal intervals within the case 20, each capacitor element 10 does not have to be housed at equal intervals within the case 20. The planar portions 29 are also arranged to match the arrangement of each capacitor element 10, so they do not have to be provided at equal intervals.

[0075] Furthermore, although the above embodiment explained that the case 20 can be manufactured by methods such as casting, cutting, and forging, the case 20 and the projection 28 may be manufactured separately.

[0076] In the above embodiment, a case was described in which a projection 28 is provided on the inner surface of the case 20 and the capacitor element 10 is housed in close proximity to the flat portion 29 formed on the projection 28. However, the projection on the inner surface of the case 20 does not need to be provided.

[0077] Furthermore, the filling resin 50 may be filled into the small case 40 first and then into the case 20, or it may be filled into both the small case 40 and the case 20 simultaneously. [Industrial applicability]

[0078] The film capacitor of the present invention can be suitably used as a motor drive capacitor, such as for in-wheel motors in electric vehicles (EVs). [Explanation of Symbols]

[0079] 1: Film capacitor 10: Capacitor element 11a: Electrode 11b: Electrode 20: Case 24: Bottom wall 25:Outer wall 26: Inner wall 29: Flat part 40: Small case 42: Crushed Ribs 50: Filling resin

Claims

1. A film capacitor comprising a plurality of capacitor elements, a case for housing the capacitor elements, and a filling resin filled inside the case, The case comprises a bottom wall having a circular or arc-shaped outer edge and a circular or arc-shaped inner edge on the central side of the circular or arc-shaped outer edge, an outer wall erected from the outer edge, and an inner wall erected from the inner edge. A film capacitor characterized in that the electrodes of the capacitor element are arranged radially inward and outward within the case, and the capacitor element is housed in a circumferential arrangement within the case.

2. A flat portion is formed on the inner side of the case of the inner wall and on the inner side of the case of the outer wall. The film capacitor according to claim 1, wherein the capacitor elements are arranged facing the planar portion.

3. Each of the aforementioned capacitor elements is housed in a small case made of an insulating material. The film capacitor according to claim 1 or 2, wherein the small case is housed in the case.

4. The film capacitor according to claim 3, wherein the filling resin is filled inside the small case in which the capacitor element is housed.

5. Crush ribs are provided on the outer surface of the small case on both electrode sides. The film capacitor according to claim 3, wherein the small case is press-fitted with respect to the case, the crush ribs are in contact with the outer wall and the inner wall of the case.

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