Film capacitor

Abstract

To provide a film capacitor of a hard core which achieves high heat radiation performance.SOLUTION: A capacitor (1) of a hard core includes a metal winding core (10), an insulation resin layer (12) formed on the side face of the winding core, and a film (20) which is wound around the insulation resin layer and forms the capacitor.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] A film capacitor is formed by winding a film around a winding core. There are two types of such winding cores: a soft core and a hard core.

[0003] Generally, in a film capacitor with a soft core, after winding the film around a temporary winding core, the temporary winding core is removed and a metal heat dissipation member is inserted instead. Therefore, a gap is generated between the heat dissipation member and the film, resulting in poor thermal conductivity. Also, when the temporary winding core is removed, the wound film loosens, creating gaps between the films and causing variations in quality.

[0004] After that, the mold resin is poured and cured, resulting in a state that is substantially gap-free. However, the films are separated from each other between the films and between the film and the heat dissipation member. As a result, in a film capacitor with a soft core, non-uniform electrical characteristics and low heat dissipation performance can occur.

[0005] Also, in a film capacitor with a hard core, the film is directly wound around the winding core and the mold resin is encapsulated without removing the winding core. Therefore, the film in the product remains tightly wound with small gaps, enabling the quality to be stabilized. Patent Document 1 describes an example of a film capacitor with a hard core.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the structure of the above-mentioned hard-core film capacitor, from the viewpoint of insulation with the film, a resin core was used for the core, and the thermal conductivity was not good.

[0008] One aspect of the present invention aims to achieve high heat dissipation performance in a hard-core film capacitor.

Means for Solving the Problems

[0009] In order to solve the above problems, the film capacitor according to the present invention is a hard-core film capacitor, comprising a metal core, an insulating resin layer formed on the side surface of the core, and a film wound around the insulating resin layer to form a capacitor.

[0010] In order to solve the above problems, the film capacitor according to the present invention is a hard-core film capacitor, comprising a core formed of a resin containing a filler for improving thermal conductivity, and a film wound around the core to form a capacitor.

[0011] In order to solve the above problems, the method for manufacturing a film capacitor according to the present invention is a method for manufacturing a hard-core film capacitor, comprising the steps of preparing a metal core, forming an insulating resin layer on the side surface of the core, and winding a film for forming a capacitor around the insulating resin layer.

[0012] In order to solve the above problems, the method for manufacturing a film capacitor according to the present invention is a method for manufacturing a hard-core film capacitor, comprising the steps of preparing a core formed of a resin containing a filler for improving thermal conductivity, and winding a film for forming a capacitor around the core.

Effects of the Invention

[0013] According to one aspect of the present invention, since the film can be tightly wound around the winding core, high thermal conductivity and heat dissipation can be achieved.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0015] 〔Embodiment 1〕 Hereinafter, embodiments according to one aspect of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0016] FIG. 1 is a perspective view showing the configuration of a capacitor 1 according to Embodiment 1. However, the mold resin is not shown. As shown in FIG. 1, the capacitor 1 includes a winding core 10, a film 20, a metallicon electrode 21, a heat dissipation member 30, and a mold resin 50. The capacitor 1 is a film capacitor in which the film 20 is wound around the winding core 10. FIG. 2 is a cross-sectional view of the capacitor 1 according to Embodiment 1.

[0017] (Configuration of Capacitor 1) The winding core 10 is a metal rod 11 which is a solid metal bar or a hollow tube made of metal. An insulating resin layer 12 is formed on the side surface of the winding core 10. The insulating resin layer 12 may be either a thermoplastic resin or a thermosetting resin. For example, from the viewpoint of insulation performance, the insulating resin layer 12 is preferably polybutylene terephthalate (PBT) or polystyrene (PS), etc.

[0018] The film 20 includes a pair of metallized films that form a capacitor. The metallized film is formed by forming a metal film on a dielectric film.

[0019] The metallicon electrodes 21 are respectively formed on both end faces of the wound film 20. One metallicon electrode 21 is connected to the metal film of one metallized film, and the other metallicon electrode 21 is connected to the metal film of the other metallized film. The metallicon electrodes 21 are formed by spraying metal on the wound film 20.

[0020] The film 20 that forms a capacitor is wound around (the surface of) the insulating resin layer 12. Also, at both ends of the insulating resin layer 12, there are portions 13 where the film 20 is not wound. The surface roughness of this portion 13 where the film is not wound is rougher than that of the portion where the film is wound. That is, the insulating resin layer 12 is formed such that the surface roughness of the portion 13 in contact with the mold resin 50 is rougher than the surface roughness of the portion where the film is wound.

[0021] Here, the capacitor 1 is molded by the mold resin 50, collectively molding the winding core 10 and the film 20 wound around the winding core 10. Thereby, it is possible to prevent the intrusion of moisture and the like into the capacitor 1 and prevent performance deterioration. Also, the mold resin 50 insulates between the film 20 and the heat dissipation member 30.

[0022] However, if the surface roughness in portion 13 is fine, the degree of bonding between the mold resin 50 and the insulating resin layer 12 may be low. Therefore, a gap may occur at the interface between the mold resin 50 and the insulating resin layer 12, and problems such as electric discharge may occur between the film 20 and the heat dissipation member 30. Here, due to the rough surface roughness of portion 13, the mold resin 50 can be firmly bonded to the insulating resin layer 12, and problems such as performance deterioration can be prevented.

[0023] The end portion of the winding core 10 is not covered with the insulating resin layer 12, and the metal rod 11 is exposed. The exposed portion of this metal rod 11 is in contact with the heat dissipation member 30. Also, the heat dissipation member is preferably made of metal for heat dissipation performance and is not in contact with the film 20. That is, the heat dissipation member 30 is in contact with the end portion of the winding core 10 and is not in contact with the film 20. The heat dissipation member 30 is a metal plate material, and a hole for fitting the winding core 10 may be formed.

[0024] Note that on the surface of the winding core 10, the insulating resin layer 12 may not be formed at the location where the winding core 10 is connected to the heat dissipation member 30. That is, the insulating resin layer 12 only needs to be formed at least in the portion where the film 20 is wound.

[0025] FIG. 3 is a diagram showing the flow of manufacturing the capacitor 1. First, a metal winding core 10 is prepared (S1).

[0026] An insulating resin layer 12 is formed on the side surface of the winding core 10 (S2). The insulating resin layer 12 may be formed by applying resin to the surface of the winding core 10, or may be formed by molding with a mold.

[0027] Next, by performing a surface treatment on the insulating resin layer 12, the surface roughness of the portion of the insulating resin layer 12 where the film 20 is not wound is made rougher than the portion where the film 20 is wound (S3). When the insulating resin layer 12 is formed by molding with a mold, the surface roughness can be made rougher by providing fine irregularities on the surface of the mold. In this case, the surface treatment can be omitted.

[0028] The film 20 is wound around the insulating resin layer 12 (S4).

[0029] By spraying metal on both end faces of the film 20, the metallicon electrode 21 is formed (S5). The winding core 10 is connected to the heat dissipation member 30.

[0030] The winding core 10, the insulating resin layer 12, the film 20, the metallicon electrode 21, and the heat dissipation member 30 are molded and sealed with the mold resin 50 (S6).

[0031] (Winding of the film 20) The film 20 is wound around the insulating resin layer 12 formed on the side surface of the winding core 10. Since the winding core 10 is made of metal having sufficient strength, the film 20 can be wound tightly. Therefore, in the capacitor 1, variations in quality due to a decrease in the adhesion between the films 20 caused by the film 20 loosening are less likely to occur.

[0032] Also, although the film 20 is wound indirectly around the metal rod 11, the insulation between the metal rod 11 and the film 20 is ensured by the interposition of the insulating resin layer 12. Therefore, within the range of the dielectric strength of the insulating resin layer 12, insulation can be ensured.

[0033] (Heat dissipation) Since the winding core 10 includes the metal rod 11, it has good thermal conductivity. Thereby, the heat generated by the flow of current in the film 20 can be efficiently transferred to the winding core 10.

[0034] In particular, in the case of the hard-core capacitor 1, since the film 20 adheres closely to the insulating resin layer 12 on the winding core 10, the thermal conductivity is good. Therefore, the heat of the film 20 can be efficiently transferred to the winding core 10.

[0035] Also, the winding core 10 and the heat radiating member 30 are in contact without passing through the insulating resin layer 12. Therefore, heat can be efficiently radiated from the heat radiating member 30. Here, the heat radiating member 30 may be directly connected to a housing (not shown) that houses the capacitor 1.

[0036] (Integrated Capacitor 2) FIG. 4 is a diagram showing an overview of an integrated capacitor 2 in which a plurality of capacitors 1 according to Embodiment 1 are aggregated. The integrated capacitor 2 includes a plurality of capacitors 1, a heat radiating member 30, and a housing 40. The integrated capacitor 2 stores a plurality of capacitors 1 inside the housing 40. The plurality of capacitors 1 are sealed by injecting and molding a mold resin (not shown) into the housing 40 in a state where the plurality of capacitors 1 are grouped together.

[0037] Note that the plurality of capacitors 1 may be connected to one heat radiating member 30. Thereby, heat can be radiated efficiently. Also, the heat radiating member 30 may be connected to the housing 40. Thereby, heat can be radiated more efficiently.

[0038] 〔Embodiment 2〕 Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0039] FIG. 5 is a cross-sectional view of the capacitor 3 according to Embodiment 2. Unlike the capacitor 1, the capacitor 3 has a winding core 14 instead of the winding core 10. The winding core 14 is not made of metal but is a resin-made winding core. However, the winding core 14 is formed of a resin containing a filler for improving thermal conductivity. Therefore, the winding core 14 has high thermal conductivity. Also, since the winding core 14 is resin, it also has high insulation. The filler for improving thermal conductivity is a filler in which the resin containing the filler has a higher thermal conductivity than the resin not containing the filler. Examples of the filler contained in the winding core 14 include fillers containing Si, AlN, or Al2O3. A step in contact with the heat dissipation member 30 may be formed on the side surface of the winding core 14.

[0040] The film 20 is wound around the winding core 14 to form a capacitor. Also in the capacitor 3, since the winding core 14 contains a filler having high thermal conductivity, the winding core 14 can absorb the heat generated in the film 20 and efficiently dissipate the heat through the heat dissipation member 30.

[0041] Note that also in Embodiment 2, as in Embodiment 1, the surface roughness of the portion 13 where the film 20 is not wound is rougher than the portion where the film 20 is wound on the side surface of the winding core 14. Further, the heat dissipation member 30 is in contact with the end of the winding core 14 and not in contact with the film 20. Thereby, the capacitor 3 can have high insulation.

[0042] FIG. 6 is a diagram showing a process for manufacturing the capacitor 3. First, a winding core 14 formed of a resin containing a filler for improving thermal conductivity is prepared (S11). The winding core 14 is formed by molding with a mold.

[0043] Next, by performing surface treatment on the surface of the core 14, the surface roughness of the portion of the core 14 where the film 20 is not wound is made rougher than the portion where the film 20 is wound (S12). Note that by providing fine irregularities on the surface of the mold at the stage of forming the core 14, the surface roughness can be made rougher. In this case, the surface treatment can be omitted.

[0044] The film 20 is wound around the core 14 (S4). By spraying metal on both end faces of the film 20, the metallicon electrode 21 is formed (S5). The core 14 is connected to the heat dissipation member 30.

[0045] The core 14, the film 20, the metallicon electrode 21, and the heat dissipation member 30 are molded and sealed with the mold resin 50 (S6).

[0046] 〔Summary〕 The film capacitor according to Embodiment 1 of the present invention is a hard-core film capacitor, and includes a metal core, an insulating resin layer formed on the side surface of the core, and a film wound around the insulating resin layer to form a capacitor.

[0047] According to the above configuration, the film can be tightly wound around the core. Therefore, a film capacitor having high electrical characteristics can be manufactured. Further, since the core is made of metal, it has a large heat capacity and can improve the heat dissipation performance of the film.

[0048] The film capacitor according to Embodiment 2 of the present invention may have a configuration in which, in the above Embodiment 1, the surface roughness of the portion of the insulating resin layer where the film is not wound is rougher than the portion where the film is wound.

[0049] According to the above configuration, due to the rough surface roughness of the portion where the film is not wound, the adhesion between the mold resin and the portion is enhanced, and high insulation performance is exhibited.

[0050] The film capacitor according to Embodiment 3 of the present invention is a hard-core film capacitor, and includes a winding core formed of a resin containing a filler for improving thermal conductivity, and a film wound around the winding core to form a capacitor.

[0051] According to the above configuration, the film can be tightly wound around the winding core. Therefore, a film capacitor having high electrical characteristics can be manufactured. In addition, since the winding core has high thermal conductivity, the heat dissipation performance of the film can be improved.

[0052] The film capacitor according to Embodiment 4 of the present invention may be configured such that, in the above Embodiment 3, the surface roughness of the portion of the side surface of the winding core where the film is not wound is rougher than the portion where the film is wound.

[0053] According to the above configuration, due to the rough surface roughness of the portion where the film is not wound, the adhesion between the mold resin and this portion is enhanced, and high insulation performance is exhibited.

[0054] The film capacitor according to Embodiment 5 of the present invention may be configured to further include a heat dissipation member that contacts the end of the winding core and does not contact the film in any of the above Embodiments 1 to 4.

[0055] According to the above configuration, the heat dissipation member can efficiently transfer heat from the winding core to the heat dissipation member and dissipate the heat.

[0056] The method for manufacturing a film capacitor according to Embodiment 6 of the present invention is a method for manufacturing a hard-core film capacitor, and includes a step of preparing a metal winding core, a step of forming an insulating resin layer on the side surface of the winding core, and a step of winding a film for forming a capacitor around the insulating resin layer.

[0057] According to the above configuration, the film can be tightly wound around the winding core. Therefore, a film capacitor having high electrical characteristics can be manufactured. Further, since the winding core is made of metal, it has a large heat capacity and can improve the heat dissipation performance of the film.

[0058] In the method for manufacturing a film capacitor according to Aspect 7 of the present invention, in the above Aspect 6, in the step of forming the insulating resin layer, the surface roughness of the portion of the insulating resin layer where the film is not wound may be made rougher than the portion where the film is wound.

[0059] According to the above configuration, due to the rough surface roughness of the portion where the film is not wound, the adhesion between the mold resin and the portion is enhanced, and high insulation performance is exhibited.

[0060] The method for manufacturing a film capacitor according to Aspect 8 of the present invention is a method for manufacturing a hard-core film capacitor, including the step of preparing a winding core formed of a resin containing a filler for improving heat conductivity, and the step of winding a film for forming a capacitor around the winding core.

[0061] According to the above configuration, the film can be tightly wound around the winding core. Therefore, a film capacitor having high electrical characteristics can be manufactured. Further, since the winding core has high heat conductivity, the heat dissipation performance of the film can be improved.

[0062] In the method for manufacturing a film capacitor according to Aspect 9 of the present invention, in the above Aspect 8, in the step of preparing the winding core, the surface roughness of the portion of the side surface of the winding core where the film is not wound may be made rougher than the portion where the film is wound.

[0063] According to the above configuration, due to the rough surface roughness of the portion where the film is not wound, the adhesion between the mold resin and the portion is enhanced, and high insulation performance is exhibited.

[0064] [Supplementary Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Description of Reference Numerals]

[0065] 1, 3 Capacitor 2 Aggregate Capacitor 10, 14 Core 11 Metal Rod 12 Insulating Resin Layer 20 Film 21 Metallic Electrode 30 Heat Dissipating Member

Claims

1. A hard-core film capacitor, comprising: a metal winding core; an insulating resin layer formed on the side surface of the winding core; a film wound around the insulating resin layer to form a capacitor.

2. The film capacitor according to claim 1, wherein the surface roughness of the portion of the insulating resin layer where the film is not wound is rougher than that of the portion where the film is wound.

3. A hard-core film capacitor, comprising: a winding core formed of a resin containing a filler for improving thermal conductivity; a film wound around the winding core to form a capacitor.

4. The film capacitor according to claim 3, wherein the surface roughness of the portion of the side surface of the winding core where the film is not wound is rougher than that of the portion where the film is wound.

5. The film capacitor according to any one of claims 1 to 4, further comprising a heat dissipation member that contacts the end of the winding core and does not contact the film.

6. A method for manufacturing a hard-core film capacitor, comprising: providing a metal winding core; forming an insulating resin layer on the side surface of the winding core; winding a film for forming a capacitor around the insulating resin layer.

7. The method for manufacturing a film capacitor according to claim 6, wherein in the step of forming the insulating resin layer, the surface roughness of the portion of the insulating resin layer where the film is not wound is made rougher than that of the portion where the film is wound.

8. A method for manufacturing a hard-core film capacitor, comprising: providing a winding core formed of a resin containing a filler for improving thermal conductivity; winding a film for forming a capacitor around the winding core.

9. The method for manufacturing a film capacitor according to claim 8, wherein in the step of providing the winding core, the surface roughness of the portion of the side surface of the winding core where the film is not wound is made rougher than that of the portion where the film is wound.

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