JP6649096B2 - Film capacitors, connected capacitors, inverters and electric vehicles - Google Patents

Description

  The present invention relates to a film capacitor, a connection type capacitor, an inverter, and an electric vehicle.

  A film capacitor is formed, for example, by winding a metallized film having a dielectric film made of a polypropylene resin into a film and an electrode film formed by vapor deposition on the surface of the dielectric film around a metal core, and forming a capacitor body. (Hereinafter referred to as a main body) (for example, refer to Patent Document 1), and terminal electrodes formed of metallikon are provided at both ends in the axial direction of the main body.

  In such a film capacitor, the metal core is used without being extracted. Since the metal core has good heat conduction and high thermal and mechanical strength, it excels in heat dissipation and does not loosen or deform the metallized film even when used at relatively high temperatures. The use of the core was easy, and the metallized film having high hardness could be wound.

  Further, in recent film capacitors, for the purpose of reducing production loss and material loss, the capacity and size per film capacitor have been increasing. For the purpose of saving space, a film capacitor having an oval cross section by flattening is often used. In such an oval film capacitor, a cylindrical core is usually used, and flattening is performed together with the element without removing the core.

JP-A-64-55816

  However, in performing the flattening process, the metal core is extremely difficult to process because the mechanical strength is too high, and there is a high possibility that the film will be damaged during the flattening process. In particular, when a cylindrical core is used, the core may be locally bent to loosen the film, and a gap may be formed between the films. When a metallikon electrode is formed as an external electrode in a state where there is a gap between the films as described above, there is a problem that the metallikon invades the gap and a short circuit occurs.

  The present invention has been made in view of the above problems, and has as its object to provide a film capacitor and a connection type capacitor having high insulating properties, and an inverter and an electric vehicle using the same.

The film capacitor of the present invention includes a main body composed of a core and a metallized film wound around the core, and a pair of terminal electrodes provided on both end surfaces in the axial direction of the main body. In addition, the core body has a cross section perpendicular to the axial length direction, a rectangular outer periphery including a pair of linear first long sides and a pair of first short sides, and a pair of sections along the first long side. A second long side, and an inner periphery having a pair of second short sides connecting the pair of second long sides, comprising a tubular member made of an insulating material, wherein the tubular member is 1 is the thickness between the short sides and the second short side, the first long side and much larger than the thickness between the second long side, the inner member is disposed inside of the inner peripheral , internal member, to characterized in that the Young's modulus is formed by a high material than the material of the tubular member .
Further, the film capacitor of the present invention comprises a main body composed of a core and a metallized film wound on the core, and a pair of terminal electrodes provided on both end surfaces in the axial direction of the main body. In addition, the core body has a cross section perpendicular to the axial direction, a rectangular outer periphery including a pair of linear first long sides and a pair of first short sides, and the first long side. A pair of second long sides along the inner periphery having a pair of second short sides connecting the pair of second long sides, a cylindrical member made of an insulating material, and the cylindrical member is The thickness between the first short side and the second short side is larger than the thickness between the first long side and the second long side, and each of the pair of second short sides has An opening, a pair of grooves extending in the axial length direction, wherein the groove is an opening located on the second short side. It extends to each of the first short side adjacent, and having a bottom to the first short side.

A connection type capacitor according to the present invention is characterized in that a plurality of the above-mentioned film capacitors are connected by a bus bar.

  The inverter according to the present invention includes a bridge circuit including a switching element, and a capacitor connected to the bridge circuit, wherein the capacitor is the above-described film capacitor or connection type capacitor.

  An electric vehicle according to the present invention includes a power supply, the above-described inverter connected to the power supply, a motor connected to the inverter, and wheels driven by the motor.

  According to the present invention, it is possible to provide a film capacitor and a connection type capacitor having high insulating properties, and an inverter and an electric vehicle using the same.

FIGS. 3A and 3B schematically show the configuration of a film capacitor, wherein FIG. 3A is a side view and FIG. It is a longitudinal cross-sectional view of a film capacitor. FIGS. 1A and 1B schematically show a film capacitor of the present embodiment, in which FIG. 1A is a cross-sectional view of a main body, FIG. 1B is a cross-sectional view of a core, and FIG. is there. (A) is a cross-sectional view showing an example of a core body, and (b) is a cross-sectional view showing an example of a core body after flattening processing. (A)-(c) is a cross-sectional view which shows the example of a cylindrical member. (A), (b) is a cross-sectional view which shows another example of a cylindrical member. FIGS. 1A and 1B schematically show a film capacitor according to an embodiment of the present invention, in which FIGS. It is a perspective view which shows a connection type capacitor typically. FIG. 2 is a schematic configuration diagram for describing a configuration of an inverter. It is a schematic structure figure showing an electric vehicle.

  1A and 1B schematically show the configuration of an embodiment of a film capacitor A, wherein FIG. 1A is a side view, and FIG. 1B is an exploded perspective view. Each drawing is provided with xyz coordinate axes for ease of explanation.

  As shown in FIG. 1B, the film capacitor A is insulated with two types of metallized films 5a and 5b having electrode films 3a and 3b, respectively, on the main surfaces of dielectric films 1a and 1b. It has a main body 7 wound around a core 6 made of a material. Terminal electrodes 8a and 8b are provided on both end surfaces of the main body 7 in the axial length direction (z direction) of the core body 6, respectively. The terminal electrode 8a is connected to the electrode film 3a, and the terminal electrode 8b is connected to the electrode film 3b. Connected to.

  In FIG. 1B, the thicknesses of the dielectric films 1a and 1b and the electrode films 3a and 3b are described to be thicker in order to facilitate understanding. In FIG. 1B, the terminal electrodes 8a and 8b are omitted.

The metallized film 5a is obtained by forming an electrode film 3a on one surface of a dielectric film 1a, and has an exposed portion 9a where the dielectric film 1a is exposed on a part of one surface. . The metallized film 5b is obtained by forming the electrode film 3b on one surface of the dielectric film 1b, and has an exposed portion 9b where the dielectric film 1b is exposed on a part of one surface. . As shown in FIG. 1B, these metallized films 5a and 5b are laminated and wound around the core 6 with a slight shift in the width direction (z direction).

  Then, the metallized films 5a and 5b are pressurized when being laminated and wound around the core 6, and as shown in FIG. 2, portions where there are gaps (exposed portions 9a and 9b) between the dielectric films 1a and 1b. In S1, the dielectric films 1a and 1b are joined together to eliminate a gap, and one side of the electrode films 3a and 3b in the axial length direction (z direction) is covered with the dielectric films 1a and 1b. The second terminal electrode 8b is insulated, and the electrode film 3b and the first terminal electrode 8a are insulated.

  A portion S2 (a portion where the metallized films 5a and 5b are shifted in the width direction (z direction)) where there is a gap between the dielectric films 1a and 1b and the electrode films 3a and 3b has a gap. The terminal electrode 8a is connected to the electrode film 3a, and the terminal electrode 8b is connected to the electrode film 3b by disposing the material forming the terminal electrodes 8a and 8b.

  In the present embodiment, the core 6 includes a cylindrical member 6a. As shown in FIGS. 3A and 3B, the tubular member 6a has a pair of linear first lengths each having a cross section perpendicular to the axial length (z direction) (hereinafter, also referred to as a cross section). A rounded rectangular outer periphery 11 having a side 11a and a pair of first short sides 11b, a pair of second long sides 12a along the first long side 11a inside the outer periphery 11, and a pair of second short sides connecting these And an inner circumference 12 having an inner periphery 12b. Here, a direction parallel to the first long side 11a is defined as an x direction, and a direction perpendicular to the first long side 11a is defined as a y direction.

  In the transverse section of the cylindrical member 6a, the length of the outer periphery 11 in the x direction may be referred to as a major axis, and the length in the y direction may be referred to as a minor axis. Further, a case where a portion where the first long side 11a and the second long side 12a are located of the tubular member is referred to as a long side, and a portion where the first short side 11b and the second short side 12b are located is referred to as a short side. There is.

  The rounded rectangular shape refers to a rectangular shape having a pair of long sides and a pair of short sides and having rounded corners, in other words, an elliptical shape having a pair of linear long sides. Here, the first long side 11a is configured by a straight line, and the first short side 11b connecting the opposed first long sides 11a is in an arc shape.

  The first long side 11a is linear, but may be slightly convex outward. The first short side 11b may have a straight line portion, but is desirably formed of a curved line having an outwardly convex arc shape, particularly a semicircle. The first long sides 11a facing each other may have a slight angle, but are preferably parallel. Further, the lengths of the opposed first long sides 11a may be different, but are desirably the same length. In the present embodiment, it is important that the outer periphery 11 does not have an inwardly concave portion.

  Since the outer periphery 11 of the cross section of the core body 6 (the tubular member 6a) has a rounded rectangular shape, local bending of the core body 6 and loosening of the metalized films 5a and 5b can be suppressed. As a result, the metallikon, which is a constituent material of the terminal electrodes 8a and 8b, hardly penetrates into the gap between the metallized films 5a and 5b, and the film capacitor A having a low short-circuit rate and high insulation can be obtained.

  Further, as shown in FIG. 3C, the cylindrical member 6a has a thickness t2 on the short side portion larger than a thickness t1 on the long side portion. The thickness t1 at the long side is the thickness between the first long side 11a and the second long side 12a, and the thickness t2 at the short side is the first short side 11b and the second short side 12b. Between the wall thickness. The thickness of the long side of the tubular member 6a at the center in the x direction is used as t1, and the thickness of the short side of the tubular member 6a at the center in the y direction is used as t2. The average value of the thickness at the long side may be used as t1, and the average value of the thickness at the short side may be used as t2.

  The shape of the cross section of the core 6 (the cylindrical member 6a) may be confirmed by, for example, performing image processing on a photograph of the cross section of the core 6 and the like.

  Such a film capacitor A can be manufactured, for example, as follows. As the element body of the cylindrical member 6a, a cylindrical element body 6α whose wall thickness in the x direction in the cross section is larger than wall thickness in the y direction is prepared. As shown in FIG. 4A, for example, a cross section of the cylindrical element body 6α having a circular outer periphery and an inner periphery having a radius in the x direction larger than a radius in the y direction is used.

  A reinforcing member 6β is arranged at a portion where the thickness of the cylindrical body 6α is small (a portion where the inner peripheral radius is large) to form a core body. Here, the reinforcing member 6β is arranged along the inner periphery of the cylindrical element body 6α. It is preferable that a pair of reinforcing members 6β having the same shape are arranged in a pair of upper and lower portions in the y-direction and point-symmetrically with respect to the center of the cylindrical element body 6α.

  The above-mentioned metalized films 5a and 5b are laminated and wound around this core body. At this time, the metallized films 5a and 5b are laminated and wound slightly shifted from each other in the width direction (z direction) of the film.

  The obtained wound body 7 is pressed together with the core body and flattened into a shape as shown in FIG. At this time, the pressing direction is set to the y direction in which the thickness of the cylindrical body 6α is small, so that the cylindrical body 6α has a pair of linear cross sections as shown in FIG. A rounded rectangular outer periphery 11 having a first long side 11a and a pair of first short sides 11b; a pair of second long sides 12a along the first long side 11a inside the outer periphery 11; And an inner periphery 12 having two short sides 12b.

  In such a tubular member 6a, the entire outer periphery 11 includes a pair of linear first long sides 11a and a pair of first short sides 11b. In addition, as shown in FIG. 3C, the thickness (t2) of the short side portion is larger than the thickness (t1) of the long side portion of the cross section. Since t2 is larger than t1, the short sides at both ends in the x direction of the cylindrical member 6a are reinforced, and in the latter stage of the flattening process by pressing the main body 7 as a wound body, When short sides are formed at both ends in the x direction of 6α, occurrence of abnormal deformation of the short sides can be suppressed.

  By arranging the reinforcing member 6β at a portion where the thickness of the tubular element body 6α is small, a portion to be a long side portion of the tubular member 6a is locally bent at the time of pressing (hereinafter simply referred to as a cylinder). Local deformation of the shaped member 6a) can be suppressed. By suppressing the local deformation of the cylindrical member 6a in this manner, loosening of the metallized films 5a and 5b and generation of voids between the metallized films 5a and 5b (hereinafter collectively referred to simply as Voids) can be suppressed, and the film capacitor A having high insulating properties can be obtained.

  After the pressing, the reinforcing member 6β may be removed, but without removing the reinforcing member 6β, the core as shown in FIG. 4B is used together with the cylindrical member 6a as the internal member 6b disposed inside the inner periphery of the cylindrical member 6a. Preferably, the body 6 is constituted.

  The cylindrical member 6a may have a groove 13 that opens in the second short side 12b and extends in the axial direction. The groove 13 extends from one end in the axial direction to the other end. The groove 13 extends from the opening (O) located on the second short side 12b to the adjacent first short side 11b side, and has a bottom (P) on the first short side 11b side (FIG. 4 (b) )). Such a groove 13 is formed by folding the inner periphery of the cylindrical element 6α near both ends in the x direction when short sides are formed at both ends in the x direction of the cylindrical element 6α by pressing. Is done. The groove 13 may be formed on each short side of the tubular member 6a (grooves 13a, 13b). For ease of description, the length of the groove 13 in the x direction is exaggerated in each cross-sectional view.

  In a cross section (transverse cross section) perpendicular to the axial direction, the inner circumference 12 of the cylindrical member 6a has a line (OO ′) connecting the opening (O) of the groove 13a and the opening (O ′) of the groove 13b. ), It is preferable to have a line-symmetric shape. For example, a pair of trapezoids having the first base 14 on the OO ′ line and the second long side 12a as the second base (12a) forms the first base 14 (OO ′ line). It is preferable to form a shape facing each other through the intermediary portions (FIGS. 5A and 5B). The lengths of the first base 14 and the second base 12a may be equal (FIG. 5C).

  The pair of trapezoids are preferably arranged symmetrically with respect to a line (OO ′ line) connecting the openings of the grooves 13a and 13b, but if the shape of the outer periphery 11 is not impaired, x They may be arranged offset from each other in the axial direction (FIGS. 6A and 6B). When the pair of trapezoids are arranged so as to be shifted from each other in the x-axis direction, it is preferable that they are arranged point-symmetrically with respect to the center of the outer periphery 11 of the tubular member 6a.

  Preferably, the grooves 13a, 13b are both located on the major axis of the outer periphery 11 of the tubular member 6a. Further, it is preferable that each of the pair of trapezoids formed by the inner circumference 12 is an equilateral trapezoid. Since the grooves 13a and 13b are located on the major axis and the inner periphery 12 has a pair of equal-leg trapezoidal shapes, local deformation during pressing can be made more difficult.

  In the cross section of the cylindrical member 6a, the entire length of the outer periphery 11 is A, and the length from the bottom P of the groove 13a to the bottom P 'of the groove 13b is B, as shown in FIG. The length from the opening O to the opening O 'of the groove 13b (sometimes referred to as the length of the line OO' or the length of the first base 14) is denoted by C. At this time, the value of the formula X = (A × C) / (2 × B × B) is preferably in the range of 0.8 to 1.2, particularly preferably in the range of 0.9 to 1.1. X is a shape factor of a cross section of the cylindrical member 6a, and by setting X within this range, local deformation of the cylindrical member 6a can be further suppressed.

  For example, when X is smaller than 0.8, deformation is likely to occur at the boundary between the long side and the short side at the beginning of the pressing step, and there is a concern that voids between the metallized films are likely to be generated. On the other hand, when X is larger than 1.2, abnormal deformation of the short side portion is likely to occur late in the pressing process, and there is a concern that voids between the films are likely to be generated.

  In order to form the cylindrical member 6a as described above, the inner peripheral shape of the cylindrical element body 6α may be designed so as to have the above-described shape after pressing.

  When the inner member 6b is arranged inside the inner periphery 12 of the tubular member 6a, the inner member 6b is made of a material having a higher Young's modulus than the material of the tubular member 6a. By making the Young's modulus of the inner member 6b (reinforcing member 6β) higher than that of the cylindrical member 6a (cylindrical element 6α), local bending of a portion that becomes a long side portion of the cylindrical member 6a during pressing is performed. Is less likely to occur. In addition, the elastic body of the dielectric film 1a, 1b in the pressed film capacitor A has an effect that the core body 6 is hardly deformed with respect to the elastic recovery.

  When the reinforcing member 6β is left and the inner member 6b is formed, the inner member 6b is brought into close contact with the inner periphery 12 of the tubular member 6a by pressing, and has the same shape as the inner periphery 12, ie, the opening (O) of the groove 13a. It has a shape symmetrical with respect to a line (OO 'line) connecting the opening (O') of the groove 13b, and has two independent first members 6b1 and It is composed of two members 6b2. The first member 6b1 is in contact with one second long side 12a, and the second member 6b2 is in contact with the other second long side 12a.

Explaining with reference to FIG. 4B, the first member 6b1 and the second member 6b2 are along a line (OO ′ line) connecting the opening O of the groove 13a and the opening O ′ of the groove 13b. It becomes a pair of trapezoidal shapes with the side and the second long side 12a as bases.

  The first member 6b1 and the second member 6b2 may be in contact with each other by an OO ′ line or may be separated from each other. However, when the inner member 6b has an insulating property, for example, FIG. ), It is preferable that at least a part of one end to the other end in the axial length direction (z direction) is in contact with each other. Since the first member 6b1 and the second member 6b2 are in contact with each other at least at one end from the one end to the other end in the axial direction (z direction), the metallikon forming the terminal electrodes 8a and 8b becomes the first member. Even if it enters the gap between 6b1 and the second member 6b2, conduction between the terminal electrodes 8a and 8b is suppressed, and the short-circuit rate can be reduced.

  Further, as shown in FIG. 7A, it is preferable that the first member 6b1 and the second member 6b2 are separated from each other at both ends in the axial direction (z direction). At both ends in the axial direction (z direction), metallikon penetrates into the gap between the first member 6b1 and the second member 6b2, and the anchor effect is obtained, thereby improving the bonding strength between the terminal electrodes 8a and 8b. can get. This effect can be obtained regardless of whether the internal member 6b has an insulating property or has a conductive property.

  Note that the above-described reinforcing member 6α may be removed after pressing, and another member may be arranged in the space formed by the inner periphery 12 to form the internal member 6b.

  As the material of the cylindrical member 6a, for example, polypropylene (PP, melting point: 168 ° C., Young's modulus: 1.2 GPa), polyacetal (POM, melting point: 181 ° C., Young's modulus: 2.8 GPa), polyamide (PA, melting point: 225 ° C, Young's modulus: 1.9 GPa, polyethylene terephthalate (PET, melting point: 255 ° C, Young's modulus: 3.7 GPa), polyphenylene sulfide (PPS, melting point: 290 ° C, Young's modulus: 3.3 GPa), polytetrafluoro Organic resin materials such as ethylene (PTFE, melting point: 327 ° C., Young's modulus: 0.41 GPa), and polyetheretherketone (PEEK, melting point: 374 ° C., Young's modulus: 3.5 GPa) are exemplified.

  As the material of the internal member 6b, for example, tin (melting point: 232 ° C., Young's modulus: 41.4 GPa), zinc (melting point: 420 ° C., Young's modulus: 96.5 GPa), aluminum (melting point: 660 ° C., Young's modulus: 68) .3GPa) and copper (melting point: 1083 ° C., Young's modulus: 110 GPa). Also, polyethylene terephthalate (PET, melting point: 255 ° C., Young's modulus: 3.7 GPa), polyphenylene sulfide (PPS, melting point: 290 ° C., Young's modulus: 3.3 GPa), and polyetheretherketone (PEEK, melting point: 374 ° C.) , Young's modulus: 3.5 GPa). Among these materials, a material having a higher Young's modulus than the material of the tubular member 6a may be applied. Preferably, the inner member 6b is made of an insulating material.

  It is preferable that the material of the inner member 6b is metal in terms of use as the reinforcing member 6β. When the internal member 6b is made of a conductive material such as a metal, it is preferable to provide an insulating coating on the surface of the internal member 6b exposed at both ends in the axial direction (z direction). Examples of the insulating coating include a tape, a sheet, and an adhesive made of an insulating resin such as polyimide. Further, as shown in FIG. 7B, a pair of conductive internal members 6b may be arranged at both ends in the axial direction (z direction), and these internal members 6b may be electrically insulated from each other. In order to electrically insulate the pair of internal members 6b from each other, a means such as disposing an insulating material between the pair of internal members 6b or physically separating the pair of internal members 6b may be used.

FIG. 8 is a perspective view schematically showing the configuration of the connection type capacitor C. In FIG. 8, the case and the resin for molding are omitted for easy understanding of the configuration. The connection type capacitor C of the present embodiment has a configuration in which a plurality of film capacitors A are connected in parallel by a pair of bus bars 21 and 23. The bus bars 21 and 23 are composed of external connection terminals 21a and 23a and lead terminals 21b and 23b connected to the terminal electrodes 8a and 8b of the film capacitor A, respectively.

  When the above-mentioned film capacitor A is applied to the connection type capacitor C, it is possible to obtain the connection type capacitor C having a low short-circuit rate and a high insulating property.

  The connection type capacitor C shown in FIG. 8 is arranged in the direction of the major axis of the cross section of the film capacitor A. In addition, a structure in which the film capacitors A are stacked in the direction of the minor axis of the cross section is used. However, the same effect can be obtained.

FIG. 9 is a schematic configuration diagram for explaining the configuration of the inverter. FIG. 9 shows an example of an inverter D that produces an alternating current from a direct current. As shown in FIG. 9, the inverter D of the present embodiment includes a switching element (for example, an IGBT (Insulated gate Bipolar Transistor)).
) And a diode, and a capacitor 33 disposed between input terminals of the bridge circuit 31 for voltage stabilization. Here, the film capacitor A or the connection type capacitor C described above is applied as the capacitance section 33.

  The inverter D is connected to a booster circuit 35 that boosts the voltage of the DC power supply. On the other hand, the bridge circuit 31 is connected to a motor generator (motor M) serving as a driving source.

  FIG. 10 is a schematic configuration diagram showing the electric vehicle. FIG. 10 shows an example of a hybrid vehicle (HEV) as the electric vehicle E.

  In FIG. 10, reference numeral 41 denotes a driving motor, 43 denotes an engine, 45 denotes a transmission, 47 denotes an inverter, 49 denotes a power source (battery), and 51a and 51b denote front wheels and rear wheels.

  The electric vehicle E mainly has a function of transmitting the output of a motor 41 or an engine 43 or both as a drive source to a pair of left and right front wheels 51 a via a transmission 45. 41.

  Further, the electric vehicle E shown in FIG. 10 is provided with a vehicle ECU 53 for performing overall control of the entire electric vehicle E. The vehicle ECU 53 receives a drive signal according to the driver's operation from the electric vehicle E such as an ignition key 55, an accelerator pedal (not shown), and a brake. The vehicle ECU 53 outputs an instruction signal to the engine ECU 57, the power supply 49, and the inverter 47 as a load based on the drive signal. The engine ECU 57 drives the electric vehicle E by controlling the rotation speed of the engine 43 in response to the instruction signal.

  When the inverter D using the film capacitor A or the connection type capacitor C as the capacitance unit 33 is used as, for example, the inverter 47 of the electric vehicle E as shown in FIG. 10, the film capacitor A or the connection type capacitor C is short-circuited. Since the ratio is low and the insulation is high, current control of a control device such as an ECU mounted on the electric vehicle E can be made more stable.

  The inverter D according to the present embodiment can be applied not only to the above-described hybrid vehicle (HEV) but also to various electric power conversion products such as an electric vehicle (EV), a fuel cell vehicle, an electric bicycle, a generator, and a solar cell. .

  A dielectric film having an average thickness of 2.5 μm was prepared using polyarylate (U-100, manufactured by Unitika). The dielectric film was prepared by dissolving polyarylate in toluene, applying the solution on a substrate made of polyethylene terephthalate (PET) using a coater, and forming the sheet. After the molding, heat treatment was performed at 130 ° C. to remove toluene, and a dielectric film was obtained.

  After peeling the obtained dielectric film from the substrate and slitting it to a width of 140 mm, an Al metal film having a width of 107 mm was formed on one main surface of the dielectric film as an electrode film using a metal mask by a vacuum deposition method. Formed to give a metallized film. The thickness of the metal film was 70 nm, and the sheet resistance was 8.0 Ω / □. Note that the thickness of the metal film was determined by observing a section subjected to ion milling with a scanning electron microscope (SEM). The sheet resistance (Rs) was obtained by measuring the resistance value (R) between both ends of a metal film having a width (w) of 10 mm and a length (l) of 300 mm by a two-terminal method, and calculating by the equation Rs = R × w / l. .

  The 140 mm wide metallized film was further slit to form a 55 mm wide metallized film having a 1.5 mm margin (exposed portion of the dielectric film).

  The tubular element has a cross-sectional shape as shown in FIG. 4A, that is, a 55 mm long polypropylene having a cross-sectional shape with a circular outer periphery, a large thickness in the x direction, and a small thickness in the y direction. (PP, melting point: 168 ° C., Young's modulus: 1.2 GPa) were prepared. Table 1 shows the outer diameter, the thickness in the x direction, and the thickness in the y direction of the tubular element. In addition, a metal aluminum plate (melting point: 660 ° C., Young's modulus: 68.3 GPa) was used as a reinforcing member, and a core element was disposed inside the cylindrical element. Table 1 shows the thickness and arrangement of the reinforcing members (the angle θ occupied by the reinforcing members in the cross section when the reinforcing members are disposed on the inner periphery of the tubular element).

  A 55 mm wide pair of metallized films was laminated and wound around a core element body such that the electrode films face each other with a dielectric film interposed therebetween, thereby producing a wound body. The pair of metallized films were wound in a state of being shifted by 0.5 mm from each other in the width direction (z direction), and the margin portions were arranged on different sides in the width direction (z direction). The number of windings was 642, and a wound body having an outer diameter of 12.5 mm and a width of 55.5 mm (both average values) was obtained.

  The obtained wound body was flattened by pressing together with a core element to obtain a film capacitor body. The pressing was performed under the conditions of a temperature of 120 ° C. and a pressing load of 500 gf. For comparison, a sample using a cylindrical element having a uniform thickness (Sample Nos. 16 to 18) and a sample obtained by extracting a core element and performing flattening (Sample No. 19) were also manufactured. For the core element having the cross-sectional shape shown in FIG. 4A, the pressing direction was set to the y direction in which the thickness of the cylindrical element was small.

  After the flattening process, a polyimide tape cover was provided at the end of the core body to cover the inner member. Thereafter, an alloy of zinc and tin was sprayed on the opposite end surfaces of the film capacitor body where the electrode films were exposed, and metallikon electrodes as terminal electrodes were formed to obtain a film capacitor.

  The center part of the obtained film capacitor in the width direction (z direction) was cut using a diamond wire saw, and the cross-sectional shape of the core was confirmed. In any of the cases using the core element having the cross-sectional shape shown in FIG. 4A, the core member has a cylindrical member having a rounded rectangular outer periphery and an inner periphery having a pair of trapezoids facing each other; And two internal members arranged along the inner periphery of the tubular member. In addition, each of them has a groove that opens at the center of each second short side in the y direction, extends to the adjacent first short side, and has a bottom at the first short side.

On the other hand, in the case of using a core body having a uniform thickness, a locally concave portion is formed near the center of a portion corresponding to the long side of the outer periphery, and a pair of linear long sides and a pair of short sides are formed. It did not have a rounded rectangular outer periphery with sides. Further, the inner periphery also had a shape in which two elliptical gaps were arranged. Further, when the core element body was extracted and flattened, there were bulges at both ends in the x direction near the center of the winding, and a concave portion was formed near the center in the x direction.

  With respect to the sample having the core, the thickness (the thickness in the y direction) t1 of the long side portion of the cylindrical member and the thickness (the thickness in the x direction) t2 of the short side portion were confirmed. In addition, for the sample whose outer periphery of the core was rounded and rectangular, the shape factor X of the cross section of the core was confirmed. Note that X = (A × C) / (2 × B × B), where A is the entire length of the outer periphery of the cylindrical member, and B is from the bottom of one groove to the bottom of the other groove. And C is the length from the opening of one groove to the opening of the other groove (see FIG. 5A). These were obtained by analyzing an image of a cross section of the core body taken by a digital camera using image processing software.

  The short-circuit rate and dielectric breakdown voltage (BDV) of the produced film capacitor were evaluated. The short-circuit rate was measured by measuring the resistance of the film capacitor using a multimeter, and 1 kΩ or less was regarded as short-circuit, and the ratio was determined. The breakdown voltage (BDV) is measured by applying a DC voltage to the film capacitor at a voltage increase rate of 10 V / sec from a voltage of 0 V. Immediately before the capacitance decreases by 5% or more with respect to the value of 0 V (initial value). Was determined from the voltage value. The initial value of the capacitance was measured under the conditions of AC 10 V and 1 kHz before performing the boosting test. The average value of the initial value of the capacitance was 17.7 μF. In the boosting test, when the short circuit, that is, the leakage current value exceeded 1.0 mA, the DC voltage was once returned to 0 V, and the capacitance was measured under the conditions of AC 10 V and 1 kHz, and the value was set to the initial value. When the voltage was 95% or more, the step-up test was repeated from 0 V.

  Table 2 shows the thicknesses t1 and t2 of the cylindrical member of the core, the shape factor X of the cross section, the short-circuit rate of the film capacitor, and the breakdown voltage (BDV). The values other than the short-circuit rate are average values of n = 50.

  Sample No. having a cylindrical member having a round cross section with a rounded outer periphery and a t2 larger than t1 was obtained. Samples Nos. 1 to 15 had a high short-circuit rate of 10% or less and a high dielectric breakdown voltage (BDV) of 850 V or more. In particular, the sample No. in which the shape factor X of the outer periphery of the core was in the range of 0.8 to 1.2. In the cases of 2 to 4, 7 to 9, and 12 to 14, the short-circuit rate was 4% or less and the BDV was 1000 V or more.

1a, 1b, dielectric films 3a, 3b, electrode films 5a, 5b, metallized films 6, core members 6a, cylindrical members 6b, internal members 7 ····· Main body 8a, 8b ··· Terminal electrode 11 ····· Outer periphery 11a of core (cylindrical member) ··· Long side 11b of outer periphery of core (cylindrical member) ···・ Short side 12 of outer periphery of core body (cylindrical member) ・ ・ ・ ・ ・ ・ Inner circumference 12a of cylindrical member ・ ・ ・ ・ Long side 12b of inner circumference of cylindrical member ・ ・ ・ ・ ・ ・ Inner circumference of cylindrical member 13 of the short side of the groove

Claims (10)

A body comprising a core and a metallized film wound on the core, and a pair of terminal electrodes provided on both end surfaces in the axial direction of the body, and
The core body has a cross section perpendicular to the axial direction,
A rectangular outer periphery having a pair of straight first long sides and a pair of first short sides;
A cylindrical member made of an insulating material, having a pair of second long sides along the first long side, and an inner periphery having a pair of second short sides connecting the pair of second long sides,
Tubular member, the wall thickness between the first short side and the second short sides, much larger than the thickness between the second long side and the first long side,
A film capacitor , wherein an inner member is arranged inside the inner periphery, and the inner member is made of a material having a higher Young's modulus than the material of the tubular member . 2. The film capacitor according to claim 1 , wherein the internal member includes a first member contacting one of the second long sides and a second member contacting the other of the second long sides. 3. The material constituting the inner member, a film capacitor according to claim 1 or 2, characterized in that a metal. A body comprising a core and a metallized film wound on the core, and a pair of terminal electrodes provided on both end surfaces in the axial direction of the body, and
The core body has a cross section perpendicular to the axial length direction,
A rectangular outer periphery having a pair of straight first long sides and a pair of first short sides;
A cylindrical member made of an insulating material, having a pair of second long sides along the first long side, and an inner periphery having a pair of second short sides connecting the pair of second long sides,
The cylindrical member has a thickness between the first short side and the second short side that is greater than a thickness between the first long side and the second long side, and the pair of the paired members. A pair of grooves that respectively open on the second short side and extend in the axial length direction;
The groove, the second extends to each of the first short side adjacent the opening located on the short side, off I Lum capacitor you characterized in that it has a bottom in the first short side. 5. The film capacitor according to claim 4 , wherein in a cross section perpendicular to the axial direction, the inner periphery has a line-symmetric shape with respect to a line connecting the openings of the pair of grooves. 6. In a cross section perpendicular to the axial direction, the length of the outer periphery is A, the length from one of the bottoms to the other is B, and one of the openings is the other of the openings. When the length to is C and X = (A × C) / (2 × B × B),
The X is a film capacitor according to claim 4 or 5, characterized in that in the range of 0.8 to 1.2. A connection type capacitor comprising a plurality of the film capacitors according to any one of claims 1 to 6 connected by a bus bar. An inverter comprising a bridge circuit constituted by a switching element and a capacitor connected to the bridge circuit, wherein the capacitor is the film capacitor according to any one of claims 1 to 6. Inverter. An inverter comprising a bridge circuit constituted by a switching element and a capacitor connected to the bridge circuit, wherein the capacitor is the connection type capacitor according to claim 7. . An electric vehicle comprising a power supply, the inverter according to claim 8 or 9 connected to the power supply, a motor connected to the inverter, and wheels driven by the motor.