JP2023061504A - Film capacitor and method for manufacturing film capacitor - Google Patents

Abstract

To provide a film capacitor in which a gap between an insertion member and an inner peripheral surface of a cavity is less likely to be formed and metal sprayed on both end surfaces of a wound body is less likely to intrude into the cavity.SOLUTION: A film capacitor 1 includes: a capacitor body 10 formed by superimposing a first evaporated electrode, a first film, a second evaporated electrode, and a second film in this order and winding these such that the first evaporated electrode is on the inside and the second film is on the outside; a columnar cavity 11 formed to penetrate the center of the capacitor body 10; and a winding core body 20 inserted in the cavity 11. The winding core body 20 includes a columnar shaft having a diameter smaller than that of the cavity 11, and a plurality of protrusions 22, which protrude from an outer peripheral surface of the shaft in a radial direction and go around the outer peripheral surface, are formed integrally with the shaft so as to be continuous in an axial direction, on the shaft. The protrusions 22 contact an inner peripheral surface of the cavity 11.SELECTED DRAWING: Figure 2

Description

The present invention relates to a film capacitor and a method for manufacturing a film capacitor.

Conventionally, a first electrode, a first film, a second electrode, and a second film are stacked in this order, and the winding is formed by winding such that the first electrode is on the inside and the second film is on the outside. A rotating body, a cylindrical hollow portion formed to penetrate the center of the wound body, and a cylindrical insertion member inserted into the hollow portion. A film capacitor having end face electrodes formed by thermal spraying is known. In such a film capacitor, since the cavity is filled with the inserting member, the thermally sprayed metal is prevented from entering the cavity. An example of such a film capacitor is described in Patent Document 1.

JP-A-10-303058

In the film capacitor described above, when the roundness of the insertion member is low, a gap penetrating the cavity may be formed between the outer peripheral surface of the insertion member and the inner peripheral surface of the cavity. In this case, the metal thermally sprayed on both end surfaces of the wound body enters the cavity, flows through the gap due to capillary action, and merges at the central portion. .

Accordingly, the present invention provides a film capacitor in which a gap is less likely to occur between an insertion member and an inner peripheral surface of a cavity, and metal thermally sprayed on both end surfaces of a wound body is less likely to enter into the cavity, and such a film capacitor. It aims at providing the manufacturing method of.

A first aspect of the present invention relates to a film capacitor. In the film capacitor according to this aspect, a first electrode, a first film, a second electrode, and a second film are stacked in this order, with the first electrode on the inside and the second film on the outside. It comprises a wound body formed by winding, a cylindrical hollow portion formed so as to penetrate through the center of the wound body, and an insertion member inserted into the hollow portion. Here, the insert member includes a cylindrical shank having a smaller diameter than the diameter of the cavity. A plurality of protruding portions protruding radially from the outer peripheral surface of the shaft portion and going around the outer peripheral surface of the shaft portion are formed integrally with the shaft portion so as to be continuous in the axial direction. The protrusion contacts the inner peripheral surface of the cavity.

A second aspect of the present invention relates to a method for manufacturing a film capacitor. The manufacturing method according to this aspect includes stacking a first electrode, a first film, a second electrode, and a second film in this order, with the first electrode on the inside and the second film on the outside. forming a wound body by winding with a rod-shaped winding shaft; and inserting an insertion member into a cylindrical cavity formed at the center of the wound body by removing the winding shaft. and spraying a metal on both end surfaces of the wound body into which the insertion member is inserted. Here, the insert member includes a cylindrical shank having a smaller diameter than the diameter of the cavity. A plurality of protruding portions protruding radially from the outer peripheral surface of the shaft portion and going around the outer peripheral surface of the shaft portion are formed integrally with the shaft portion so as to be continuous in the axial direction. When the insertion member is inserted into the hollow portion, the protrusion contacts the inner peripheral surface of the hollow portion.

ADVANTAGE OF THE INVENTION According to the present invention, a film capacitor that hardly creates a gap between an insertion member and an inner peripheral surface of a cavity, and that makes it difficult for metal sprayed on both end faces of a winding body to enter the cavity, and such a film capacitor. can provide a manufacturing method of

The effects and significance of the present invention will become clearer from the description of the embodiments shown below. However, the embodiment shown below is merely an example of carrying out the present invention, and the present invention is not limited to the embodiments described below.

FIG. 1(a) is a perspective view of a film capacitor according to an embodiment. FIG. 1(b) is a perspective view of the film capacitor before the formation of the first end-face electrodes and the second end-face electrodes. FIG. 2 is a cross-sectional view of the film capacitor cut along the axial direction according to the embodiment. FIG. 3(a) is a diagram showing a capacitor body in a state where the first film and part of the second film are wound according to the embodiment. FIG. 3(b) is a cross-sectional view of the capacitor body cut in the width direction at the portion of the fuse pattern according to the embodiment, and FIG. 3(c) is a portion without the fuse pattern according to the embodiment. 1 is a cross-sectional view of a capacitor body cut in the width direction at . FIG. 4(a) is a side view of the winding core according to the embodiment. FIG. 4(b) is a cross-sectional view taken along the line AA' of FIG. 4(a). FIG. 5(a) is a view showing one end of the winding core and the vicinity of the inlet of the cavity of the capacitor body according to the embodiment. FIG. 5(b) is a view showing the vicinity of the entrance of the hollow portion of the capacitor body with the winding core inserted, according to the embodiment. FIG. 6 is a flow chart showing the manufacturing process of the film capacitor according to the embodiment. FIGS. 7A and 7B are diagrams showing the configuration of the winding core according to the modified example. FIG. 8 is a diagram showing the configuration of a film capacitor according to a modification.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<Structure of film capacitor>
First, a film capacitor 1 according to this embodiment will be described. The film capacitor 1 is manufactured by the manufacturing method of the film capacitor 1 according to the present embodiment, which will be described later.

FIG. 1(a) is a perspective view of a film capacitor 1. FIG. FIG. 1(b) is a perspective view of the film capacitor 1 before the first end surface electrode 40 and the second end surface electrode 50 are formed. FIG. 2 is a cross-sectional view of the film capacitor 1 cut along the axial direction.

The film capacitor 1 includes a capacitor main body 10 that is a wound body, a winding core 20 that is an insertion member, an exterior film 30 , a first end face electrode 40 and a second end face electrode 50 . The film capacitor 1 has a cylindrical shape with a perfectly circular cross section.

Capacitor body 10 is constructed by winding two sheets of dielectric films on which vapor-deposited electrodes are formed, while being stacked. The capacitor body 10 is formed with an elongated columnar cavity 11 penetrating through the center of the capacitor body 10 . A winding core 20 is inserted into the hollow portion 11 .

The exterior film 30 is wound multiple times (multiple turns) around the outer peripheral surface of the capacitor body 10 . As a result, the outer peripheral surface of the capacitor body 10 is covered with a plurality of layers of the exterior film 30, and the capacitor body 10 is prevented from being scratched or damaged. Examples of materials for the exterior film 30 include polypropylene (PP), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

The first end surface electrode 40 and the second end surface electrode 50 are formed by spraying a metal such as aluminum, zinc, magnesium, etc. on the first end surface 12 and the second end surface 13 of the capacitor body 10, respectively. Lead terminals (not shown) such as bus bars and lead wires are connected to the first edge electrode 40 and the second edge electrode 50 in order to draw electricity from the film capacitor 1 .

Next, the configuration of the capacitor body 10 will be described in detail.

FIG. 3(a) is a diagram showing capacitor body 10 in a state in which a portion of first film 110 and second film 120 are wound. 3B is a cross-sectional view of the capacitor body 10 cut in the width direction at the fuse pattern 145 portion, and FIG. 3C is a cross-sectional view of the capacitor body cut in the width direction at the portion without the fuse pattern 145. 10 is a cross-sectional view of FIG.

The capacitor body 10 includes a first film 110, a second film 120, a first deposited electrode 130 as a first electrode, and a second deposited electrode 140 as a second electrode.

The first film 110 and the second film 120 are wound in a stacked state so that the first film 110 is inside (upper side) and the second film 120 is outside (lower side). The first film 110 and the second film 120 are transparent dielectric films made of a resin material such as polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN). The first film 110 and the second film 120 have substantially equal width dimensions. The first film 110 is formed with a first insulating margin 111 extending continuously in its longitudinal direction at one end in its width direction. The second film 120 is formed with a second insulating margin 121 continuously extending in its longitudinal direction at the end opposite to one end of the first film 110 in its width direction. The first insulating margin portion 111 and the second insulating margin portion 121 are the margin portions where no metal, ie, aluminum-containing layer is deposited.

The first deposition electrode 130 is an aluminum-containing layer and is formed on one (upper) film surface 110 a of the first film 110 . The aluminum-containing layer is formed, for example, by vapor deposition of aluminum or an alloy of aluminum and a metal such as magnesium. In addition, it is desirable that the metal to be alloyed with aluminum does not contain zinc. The first deposition electrode 130 is formed continuously without being divided in the longitudinal direction of the first film 110 . The first deposition electrode 130 is formed up to the other end in the width direction of the first film 110 and is connected to the second edge electrode 50 .

The second vapor deposition electrode 140 is an aluminum-containing layer similar to the first vapor deposition electrode 130, and has one (upper) film surface 120a of the second film 120 facing the other (lower) film surface of the first film 110. formed in The second deposition electrode 140 is formed up to the end of the second film 120 opposite to the end on the side of the second insulating margin portion 121 in the width direction, and is connected to the first end face electrode 40 .

A longitudinal slit portion 141 extending in the longitudinal direction is formed at the end portion of the second deposition electrode 140 connected to the first end face electrode 40 . In addition, the second vapor deposition electrode 140 is formed with widthwise slits 142 that cross the second vapor deposition electrode 140 in the width direction at predetermined intervals in the longitudinal direction thereof. The width direction slit portion 142 is formed from the longitudinal direction slit portion 141 to the second insulating margin portion 121 so as to be inclined with respect to the width direction. The second vapor deposition electrode 140 has a longitudinal slit portion 141 and a plurality of width direction slit portions 142, a common electrode 143 extending in the longitudinal direction and connected to the first end surface electrode 40, and a plurality of divided electrodes arranged in the longitudinal direction. and the electrode 144 .

The widths of the first insulating margin portion 111 and the second insulating margin portion 121 are significantly wider than the widths of the longitudinal slit portion 141 and the widthwise slit portion 142 .

The capacitor 10a is configured by the first vapor deposition electrode 130 and each divided electrode 144 facing the first vapor deposition electrode 130. As shown in FIG.

The capacitor body 10 includes an effective electrode region RB1 where the first vapor deposition electrode 130 and the second vapor deposition electrode 140 overlap, and a non-effective electrode region deviating from the effective electrode region RB1 in the width direction of the first vapor deposition electrode 130 and the second vapor deposition electrode 140. RB2.

The longitudinal slit portion 141 is provided in the non-effective electrode region RB2. Therefore, in the second vapor deposition electrode 140, the vicinity of the longitudinal slit portion 141 in each split electrode 144 is included in the non-effective electrode region RB2. Also, the portion of each divided electrode 144 that overlaps the first deposition electrode 130 is included in the effective electrode region RB1. Effective electrode area RB1 contributes to the capacitance of capacitor 10a.

A fuse pattern 145 is formed between each divided electrode 144 and the common electrode 143 so as to span the longitudinal slit portion 141 . The pattern width of fuse pattern 145 is set to, for example, about 0.5 mm.

Next, the configuration of the winding core 20 will be described in detail.

FIG. 4(a) is a side view of the winding core 20. FIG. FIG. 4(b) is a cross-sectional view taken along the line AA' of FIG. 4(a).

The winding core 20 is made of a resin material such as polypropylene (PP), and has an elongated columnar (round bar) shaft 21 and a plurality of projections 22 integrally formed with the shaft 21 so as to be continuous in the axial direction. including. The plurality of projecting portions 22 have an annular shape, protrude radially from the outer peripheral surface of the shaft portion 21, and circle the outer peripheral surface. Each projecting portion 22 has a substantially semicircular cross-section when cut in the circumferential direction, and the tip thereof draws an arc (see FIG. 2).

FIG. 5( a ) is a diagram showing one end of the winding core 20 and the vicinity of the inlet of the cavity 11 of the capacitor body 10 . FIG. 5(b) is a view showing the vicinity of the entrance of the hollow portion 11 of the capacitor body 10 with the winding core 20 inserted. 5(a) and 5(b) show the cross section of the hollow portion 11 of the capacitor body 10. As shown in FIG.

As shown in FIG. 5A, the diameter (outer diameter) D1 of the core body 20 is larger than the diameter (inner diameter) D2 of the hollow portion 11 of the capacitor body 10 before the core body 20 is inserted. is made as large as possible. The capacitor body 10 has a structure in which two films are wound, and the inner peripheral surface of the hollow portion 11 has a certain degree of elasticity. Therefore, as shown in FIG. 5B, when the core body 20 is inserted into the hollow portion 11, the tips of the plurality of projections 22 bite into the inner peripheral surface of the hollow portion 11. It is in contact with the inner peripheral surface. The diameter D3 (see FIG. 4) of the shaft portion 21 of the winding core 20 is smaller than the diameter D2 of the hollow portion 11. As shown in FIG.

As shown in FIGS. 2 and 5B, both end faces of the winding core 20 inserted into the hollow portion 11 are substantially flush with the end faces 12 and 13 of the capacitor body 10 .

<Manufacturing method of film capacitor>
Next, a method for manufacturing the film capacitor 1 will be described.

FIG. 6 is a flow chart showing the manufacturing process of the film capacitor 1. As shown in FIG.

As shown in FIG. 6, the manufacturing process of the film capacitor 1 includes a film winding process, an exterior film coating process, a winding core inserting process, and a metal spraying process.

First, a film winding process is performed. In the film winding process, the first film 110 having the first deposition electrode 130 formed on the upper film surface 110a is fed out from a first unwinding shaft (not shown), and the second deposition is performed on the upper film surface 120a. A second film 120 having an electrode 140 formed thereon is fed from a second unwinding shaft (not shown). The first vapor deposition electrode 130, the first film 110, the second vapor deposition electrode 140, and the second film 120 are stacked in this order, with the first vapor deposition electrode 130 on the inside and the second film 120 on the outside. and is wound up by a winding shaft (not shown). Thereby, the capacitor body 10 is formed. When the winding shaft is removed from the capacitor body 10 , an elongated cylindrical cavity 11 is formed in the center of the capacitor body 10 . The first deposition electrode 130 is not formed on the portion of the first film 110 corresponding to the inner peripheral surface of the hollow portion 11 .

Next, an exterior film coating step is performed. In the exterior film covering step, the exterior film 30 is wound a plurality of times around the outer peripheral surface of the capacitor body 10, and each layer of the exterior film 30 is heat-sealed. As a result, the outer peripheral surface of capacitor body 10 is covered with multiple layers of exterior film 30 .

Next, a winding core inserting step is performed. In the core inserting step, the core 20 is inserted into the hollow portion 11 of the capacitor body 10 . As a result, the hollow portion 11 is filled with the winding core 20 . As described above, the diameter D1 of the core body 20 is larger than the diameter D2 of the hollow portion 11 of the capacitor body 10 , so the core body 20 is press-fitted into the hollow portion 11 . As shown in FIG. 5(b), the tips of the plurality of protrusions 22 come into contact with the inner peripheral surface of the cavity 11 so as to bite into.

Since the tips of the projections 22 are arc-shaped, the first film 110, which is the inner peripheral surface of the cavity 11, is less likely to be damaged when the core 20 is press-fitted. In addition, since the first vapor deposition electrode 130 is not formed on the portion of the first film 110 corresponding to the inner peripheral surface of the hollow portion 11, the first vapor deposition electrode 130 is not damaged.

A metal spraying process is then performed. In the metal spraying process, hollow portion 11 is filled with winding core 20, and metal is sprayed onto first end face 12 and second end face 13 of capacitor body 10 from a spraying device (illustrated). As a result, the first end surface electrode 40 is formed on the first end surface 12 and the second end surface electrode 50 is formed on the second end surface 13 .

Thus, the film capacitor 1 is completed.

In the present embodiment, the core body 20 has a configuration in which a plurality of annular protrusions 22 are integrally formed on the outer peripheral surface of a cylindrical shaft portion 21 so as to be continuous in the axial direction. Compared to the case where the resin material is used for molding, sink marks are less likely to occur and the degree of circularity tends to be higher. Therefore, gaps are less likely to occur between the outer peripheral surface of the winding core 20 , that is, the tip of each protrusion 22 and the inner peripheral surface of the hollow portion 11 . Moreover, even if sink marks occur in the winding core 20, the projections 22 with low roundness are generated individually, so that there is a gap between a certain projection 22 and the inner peripheral surface of the cavity 11. Even if it does occur, it is difficult for the gap to continue in the axial direction of the winding core 20 . As a result, when the metal is thermally sprayed onto both end faces 12 and 13 of the capacitor body 10, the sprayed metal enters the hollow portion 11, flows through the gap due to capillary action, and reaches the central portion. Hateful. Therefore, in the completed film capacitor 1, short-circuiting between the first end surface electrode 40 and the second end surface electrode 50 is prevented.

Further, when the core body 20 is inserted into the hollow portion 11 , the tips of the plurality of protrusions 22 bite into the inner peripheral surface of the hollow portion 11 . As a result, the plurality of protrusions 22 are in strong contact with the inner peripheral surface of the hollow portion 11 , so that the sprayed metal is even less likely to enter the hollow portion 11 (central portion).

Further, the plurality of projections 22 are arranged in the axial direction on the outer peripheral surface of the shaft portion 21 with almost no space therebetween. This increases the number of contact areas between the outer peripheral surface of the winding core 20 and the inner peripheral surface of the hollow portion 11 , thereby making it even more difficult for the sprayed metal to enter the hollow portion 11 .

<Effect of Embodiment>
As described above, according to the present embodiment, the following effects can be obtained.

In the film capacitor 1, a first vapor deposition electrode 130, a first film 110, a second vapor deposition electrode 140, and a second film 120 are stacked in this order, with the first vapor deposition electrode 130 on the inside and the second film 120 on the outside. A capacitor body 10 formed by winding so as to be, a cylindrical hollow portion 11 formed so as to penetrate the center of the capacitor body 10, a core body 20 inserted into the hollow portion 11, Prepare. The core body 20 includes a columnar shaft portion 21 having a diameter D3 smaller than the diameter D2 of the hollow portion 11, and the shaft portion 21 protrudes in the radial direction from the outer peripheral surface of the shaft portion 21 and extends along the outer peripheral surface. A plurality of circulating protruding portions 22 are integrally formed with the shaft portion 21 so as to be connected in the axial direction. The protrusion 22 contacts the inner peripheral surface of the hollow portion 11 .

According to this configuration, a gap is less likely to occur between the winding core 20 and the inner peripheral surface of the hollow portion 11 . can be prevented from entering the hollow part 11, flowing through the gap due to capillary phenomenon and reaching the central part, and short-circuiting between the first end face electrode 40 and the second end face electrode 50 can be prevented.

Furthermore, in the film capacitor 1 , the tip of the projecting portion 22 of the winding core 20 bites into the inner peripheral surface of the hollow portion 11 .

With this configuration, the plurality of protrusions 22 are in strong contact with the inner peripheral surface of the cavity 11 , so the thermally sprayed metal is even less likely to enter the cavity 11 .

The manufacturing method of the film capacitor 1 includes stacking the first vapor deposition electrode 130, the first film 110, the second vapor deposition electrode 140, and the second film 120 in this order, with the first vapor deposition electrode 130 inside and the second film A film winding step of forming the capacitor body 10 by winding with a rod-shaped winding shaft so that 120 is on the outside, and a cylindrical film formed at the center of the capacitor body 10 by removing the winding shaft. A core inserting step of inserting the core 20 into the hollow portion 11 and a metal spraying step of thermally spraying the end surfaces 12 and 13 of the capacitor body 10 into which the core 20 is inserted are provided. The core body 20 includes a columnar shaft portion 21 having a diameter D3 smaller than the diameter D2 of the hollow portion 11, and the shaft portion 21 protrudes in the radial direction from the outer peripheral surface of the shaft portion 21 and extends along the outer peripheral surface. A plurality of circulating protruding portions 22 are integrally formed with the shaft portion 21 so as to be connected in the axial direction. When the winding core 20 is inserted into the hollow portion 11 , the protruding portion 22 comes into contact with the inner peripheral surface of the hollow portion 11 .

According to this manufacturing method, since a gap is less likely to occur between the winding core 20 and the inner peripheral surface of the hollow portion 11 , when the metal is thermally sprayed onto both end surfaces 12 and 13 of the capacitor body 10 , the thermal spraying does not occur. It is possible to prevent the metal from entering the hollow portion 11, flowing through the gap due to capillary action, and reaching the central portion. As a result, in the completed film capacitor 1, short-circuiting between the first end surface electrode 40 and the second end surface electrode 50 can be prevented.

Further, in the manufacturing method of the film capacitor 1, the diameter D1 of the core body 20 is made larger than the diameter D2 of the cavity 11 before the core body 20 is inserted, and the core body 20 is inserted into the cavity 11. is pressed in.

According to this manufacturing method, since the plurality of projections 22 are in strong contact with the inner peripheral surface of the cavity 11 , the sprayed metal is even less likely to enter the cavity 11 .

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the application examples of the present invention may be modified in various ways other than the above-described embodiments. It is possible.

FIGS. 7A and 7B are diagrams showing configurations of core bodies 20A and 20B according to a modification.

In the above-described embodiment, the winding core 20 is configured such that the plurality of protruding portions 22 are aligned in the axial direction on the outer peripheral surface of the shaft portion 21 with almost no space between them. However, instead of the core body 20, a core body 20A shown in FIG. 7(a) may be used. In the winding core 20A, a plurality of projecting portions 22 are arranged on the outer peripheral surface of the shaft portion 21 with gaps in the axial direction. For example, the gap can be made approximately the same as the width of the protrusion 22 in the axial direction.

Further, in the above-described embodiment, the core body 20 has a plurality of protrusions 22 independently provided as individual annular bodies on the outer peripheral surface of the shaft portion 21 . However, instead of the core body 20, a core body 20B shown in FIG. 7(b) may be used. In the winding core 20B, a plurality of protrusions 22 are spirally continuous on the outer peripheral surface of the shaft portion 21 .

FIG. 8 is a diagram showing the configuration of a film capacitor 1A according to a modification.

In the above embodiment, one winding core 20 is inserted into the hollow portion 11 of the capacitor body 10 . However, like the film capacitor 1A shown in FIG. In this case, each winding core 20C is inserted from each end surface 12, 13 of the capacitor body 10. As shown in FIG. As shown in FIG. 8, each winding core 20C does not have to reach the center of the hollow portion 11. As shown in FIG.

Furthermore, in capacitor body 10 of the above embodiment, first vapor deposition electrode 130 is formed on one film surface 110a of first film 110, and second vapor deposition electrode 140 is formed on one film surface 120a of second film 120. was done. However, in the capacitor body 10, the first vapor deposition electrode 130 is formed on one film surface 110a of the first film 110, the second vapor deposition electrode 140 is formed on the other film surface, and the second vapor deposition electrode 140 is formed on the second film 120. It may be configured such that 140 is not formed.

Furthermore, the configurations of the first vapor deposition electrode 130 and the second vapor deposition electrode 140 are not limited to those of the above embodiments. For example, the second vapor deposition electrode 140 does not have to be composed of the segmented electrodes 144 .

In addition, the embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea indicated in the scope of claims.

INDUSTRIAL APPLICABILITY The present invention is useful for film capacitors used in various electronic devices, electrical devices, industrial devices, electrical equipment of vehicles, etc., and methods for manufacturing such film capacitors.

1, 1A film capacitor 10 capacitor body (wound body)
11 Cavity Part 12 First End Face 13 Second End Face 20, 20A, 20B, 20C Core body (insertion member)
21 Axle 22 Projection 110 First film 120 Second film 130 First deposition electrode (first electrode)
140 second deposition electrode (second electrode)

Claims (4)

A winding formed by stacking a first electrode, a first film, a second electrode, and a second film in this order and winding such that the first electrode is on the inside and the second film is on the outside. a rotating body;
a cylindrical hollow portion formed to penetrate through the center of the wound body;
an insertion member inserted into the cavity,
the insertion member includes a cylindrical shaft portion having a diameter smaller than the diameter of the hollow portion;
A plurality of projecting portions protruding radially from the outer peripheral surface of the shaft portion and circling the outer peripheral surface of the shaft portion are integrally formed with the shaft portion so as to be continuous in the axial direction,
the protrusion contacts the inner peripheral surface of the cavity;
A film capacitor characterized by: the tip of the protrusion bites into the inner peripheral surface of the cavity,
The film capacitor according to claim 1, characterized by: A first electrode, a first film, a second electrode, and a second film are layered in this order, and wound with a rod-shaped winding shaft so that the first electrode is inside and the second film is outside. forming a wound body by
a step of inserting an insertion member into a cylindrical cavity formed at the center of the wound body by removing the winding shaft;
a step of thermally spraying a metal on both end surfaces of the wound body into which the insertion member is inserted;
the insertion member includes a cylindrical shaft portion having a diameter smaller than the diameter of the hollow portion;
A plurality of projecting portions protruding radially from the outer peripheral surface of the shaft portion and circling the outer peripheral surface of the shaft portion are integrally formed with the shaft portion so as to be continuous in the axial direction,
When the insertion member is inserted into the cavity, the protrusion contacts the inner peripheral surface of the cavity.
A method of manufacturing a film capacitor, characterized by: the diameter of the insertion member is greater than the diameter of the cavity before the insertion member is inserted;
the insertion member is press-fitted into the cavity;
4. The method of manufacturing a film capacitor according to claim 3, wherein:

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