JP5768211B2 - Case mold type capacitor - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is used in various electronic equipment, electrical equipment, industrial equipment, automobiles, etc., and in particular, a metallized film capacitor that is optimal for smoothing, filtering, and snubbing of a motor drive inverter circuit of a hybrid car is contained in a case. And a resin-molded case mold type capacitor.

  In recent years, from the viewpoint of environmental protection, many electric devices are controlled by inverter circuits, and energy saving and high efficiency are being promoted. In particular, in the automobile industry, development of technologies related to energy saving and high efficiency has been activated, such as the introduction of hybrid vehicles (hereinafter referred to as HEVs) that use electric motors and gasoline engines.

  The electric motor used in such HEV has a high operating voltage range of several hundred volts, and therefore, as a capacitor used in connection with such an electric motor, a metal having high withstand voltage and low loss electric characteristics. Film capacitors are attracting attention. Furthermore, due to the demand for maintenance-free in the market, a tendency to adopt metalized film capacitors having a very long life is conspicuous.

  When a current is passed through the metallized film capacitor, Lorentz force is generated between the metallized films by the action of electromagnetic force. And when the magnitude | size of an electric current changes or an intermittent electric current flows, this Lorentz force changes with time, and a film vibrates in the direction orthogonal to the winding axis direction of a capacitor | condenser element. Moreover, it is also converted into vibration in the winding axis direction through a mold resin filled around the capacitor element.

  This vibration is propagated from the mold resin to the case and may be a problem as noise. In particular, when such a metallized film capacitor is used for smoothing an inverter circuit for HEV, since the switching frequency is an audible frequency of several kHz to 15 kHz, it is used for automobiles that require high quietness. In this case, it is necessary to reduce the noise as much as possible, and various proposals have been made to reduce the noise generated in such a high frequency region.

  For example, in Patent Document 1, as a means for reducing the noise by the capacitor element itself, the capacitor element in which a metallized film formed by depositing a metal on a resin film is heated, and at the same time, above and below the cross section of the capacitor element and There has been proposed a manufacturing method in which the vibration of the capacitor element is reduced without increasing the occurrence of insulation failure by pressurizing from the left-right direction and heating / press-molding.

  Patent Document 2 discloses a capacitor element formed by winding a metallized film with a metal vapor deposited on one or both sides of a plastic film, and an exterior case containing one or a plurality of the capacitor elements and filled with a resin. In the metallized film capacitor provided with, by arranging a sound-absorbing soundproofing material between the outer surface of the capacitor element and the inner surface of the outer case, by reducing the vibration of the capacitor element itself, beat noise and enhancing the sound insulation effect, It is said that a metallized film capacitor with low noise and high safety can be obtained.

  Furthermore, in Patent Document 3, a positive electrode layer that charges positive charges and a negative electrode layer that charges negative charges are laminated outside via an insulating part having electrical insulation properties, and arranged outside. A positive electrode power source that is electrically connected to the positive electrode power source and that is in contact with the positive electrode layer at one of the axial ends that are both ends in the winding axis direction of the metallized film; The metallization in a cross section in a direction perpendicular to the winding axis direction of the metallized film and the negative electrode side electrode part that is electrically connected to the negative electrode power source and contacts the negative electrode layer at the other axial end An axial core disposed at the center of gravity of the film, and the axial core serves as a fixing means for fixing the capacitor single element at a predetermined position, whereby a metallized film serving as a vibration generation source Position of the center of gravity, Mari, since the axial center of gravity position as the center of the vibration are arranged, the vibration each other occurring on both sides of the gravity center position, can be more than offset in axial. Therefore, if the shaft core is arranged at the center of gravity, it can be sufficiently suppressed that the shaft core vibrates due to the vibration of the metallized film, and the other side fixing the shaft core hardly vibrates. Has been.

JP 2000-12371 A JP 2005-93515 A JP 2010-93060 A

  However, although Patent Document 1 can reduce the vibration of the capacitor element by heating and pressure-molding the capacitor element, since the vibration does not completely disappear, it is actually combined with Patent Document 2. is there.

  Further, in Patent Document 2, it is said that vibration is reduced by arranging a sound-absorbing and sound-insulating material between the outer surface of the capacitor element and the inner surface of the outer case. However, actually, the sound-absorbing and sound-insulating material is covered with a resin filled in the case. Therefore, there is a problem that vibration generated in the capacitor element propagates through the filled resin to vibrate the case and is transmitted as noise to the outside of the case.

  On the other hand, in Patent Document 3, it is said that vibration is reduced by disposing the shaft core on the positive electrode side and the negative electrode side at the center of gravity of the winding core on which the metallized film is wound. In the case of the winding process, a normal winder cannot be used in the winding process, and there is a problem that the shaft core becomes harmful when forming each electrode, and the process becomes complicated. Also, in the case of inserting the shaft core after winding the metallized film, the clearance between the wound core and the shaft core becomes a problem, and if there is even a little clearance, there is a problem that it will not be a countermeasure against vibration. ing.

  An object of the present invention is to solve such a conventional problem and to provide a case mold type capacitor which does not generate noise and has excellent reliability.

In order to achieve the above object, the present invention provides a case having an opening on the upper surface, a capacitor element housed in the case and having a pair of electrodes, and connecting electrode connection portions to the pair of electrodes of the capacitor element, respectively. In a case mold type capacitor comprising a pair of bus bars having external connection terminal portions and a mold resin filled in the case, the capacitor element has a cylindrical through hole on a peripheral surface, and the circle The columnar through hole is filled with an organic resin.

As described above, according to the present invention, the capacitor element has a cylindrical through-hole on the peripheral surface, and by filling the through-hole with an organic resin, the rigidity of the capacitor element is increased. Since the metallized film is fixed with an organic resin, even if a current flows through the capacitor element and Lorentz force is generated between the metallized films, vibration of the metallized film can be suppressed. As a result, the vibration of the capacitor element is reduced and the generation of noise in the case mold type capacitor is suppressed.

(A) Top view of a case mold type capacitor in which the capacitor element is housed in a case, (b) Front view of the same The perspective view of the capacitor | condenser element in embodiment of this invention A graph showing noise measurement results

(Embodiment 1)
FIGS. 1A and 1B are a plan view and a front view of a case mold type capacitor according to Embodiment 1 of the present invention.

  In the figure, 11 is a capacitor element, 14 is a P pole bus bar, and 15 is an N pole bus bar. The P-pole bus bar 14 includes an electrode connection portion 14 a connected to one electrode 12 of the capacitor element 11 and an external connection terminal portion 14 b, and the N-pole bus bar 15 is also connected to the other electrode 12 of the capacitor element 11. Electrode connection part (not shown) and an external connection terminal part 15b.

  Reference numeral 16 denotes a resin case which houses a plurality of capacitor elements 11 connected by a pair of bus bars 14 and 15.

  Although not shown, the case 16 is filled with mold resin so as to cover the capacitor element 11 and expose the external connection terminal portions 14b and 15b of the pair of bus bars 14 and 15.

  As shown in FIG. 2, the capacitor element 11 has a flat shape. This capacitor element 11 is a press working after winding a pair of metallized films having a metal vapor-deposited electrode formed on one or both sides of a dielectric film made of polypropylene, with the metal vapor-deposited electrodes facing each other across the dielectric film. Then, flattening is performed to make the cross section oval, and a pair of electrodes 12 of P and N poles are provided by forming metallconic electrodes sprayed with metallicon on both end faces, respectively.

  The oval capacitor element 11 preferably has a / b in the range of 1.5 to 4.0, where a is the long side of the oval cross section and b is the short side. If this a / b is less than 1.5 (low flatness), the vibration of the capacitor element 11 can be suppressed to some extent, but it is not satisfactory and cannot be reduced in size and thickness. Also, if a / b exceeds 4.0 (the flatness ratio is high), it becomes difficult to uniformly flatten the capacitor element 11, the adhesion between metallized films is poor, the capacity change rate becomes large, and there is a problem with the life characteristics. have.

  A through hole 13 penetrating in the center of the oblong shape of the capacitor element 11 is provided. The through hole 13 is filled with an organic resin (not shown). The size of the through-hole 13 is not particularly limited, but the diameter is preferably 2 to 4 mm although it depends on the size of the capacitor element 11. The through hole 13 can be opened by machining, laser processing, water jet processing, or the like.

  By filling the through hole 13 of the capacitor element 11 with an organic resin, it is possible to fix a part of the laminated layer of the metallized film, so that the vibration of the metallized film is eliminated even when an electric current is passed. 11 can be suppressed.

  As the organic resin to be filled, a mold resin filled in the case 16 can be used. At this time, the capacitor element 11 is accommodated in the case 16 so that the flat surface of the capacitor element 11 faces the bottom surface of the case 16. With this arrangement, when the capacitor element 11 accommodated in the case 16 is molded with resin, the through hole 13 is also filled, so that the manufacturing process is simplified, and the mold resin is used for the capacitor element 11. This is preferable because the through hole 13 is surely entered.

  The mold resin is preferably made of an epoxy resin as a main material and containing an inorganic filler. This shows a low value of linear expansion coefficient and cure shrinkage, so that adverse effects such as generation of cavities and expansion between metallized films can be suppressed when the through holes 13 are filled and cured.

  As the organic resin, polypropylene, polyethylene, silicon resin, fluorine resin, or the like can be used. At this time, liquid resin such as polypropylene is filled in the through holes 13 of the capacitor element 11 in advance, and then the bus bars 14 and 15 are connected and accommodated in the case 16, and the case 16 is filled with mold resin. In particular, by using the same polypropylene resin as that of the metallized film, there is no adverse effect such as generation of a cavity in the through hole 13 or expansion between the metallized films.

  Next, a specific example of this embodiment will be described.

Example 1
As a capacitor element, a dielectric film made of polypropylene having a thickness of 3 μm and a width of 50 mm is paired with a metallized film in which an aluminum vapor-deposited metal is formed on the surface thereof, and the metallized film is opposed to the dielectric film therebetween. Then, flat processing was performed to make the cross section into an oval shape (long side 50 mm, short side 35 mm, width 50 mm).

  Next, a through hole having a diameter of 3 mm was formed by machining in the center of the flattened capacitor element.

  Next, zinc metallicon electrodes were respectively formed on both end faces of the capacitor element by metallicon spraying.

  Next, as shown in FIG. 2, three capacitor elements are used, and P-pole bus bars and N-pole bus bars are connected to the metallicon electrodes, housed in a polyphenylene sulfide resin case, and an epoxy resin containing an inorganic filler in the case. Was filled with epoxy resin in the through holes of the capacitor elements, and a mold resin was filled so as to expose the external connection terminals of each capacitor element and each bus bar to produce a case mold type capacitor.

(Comparative Example 1)
A case mold type capacitor having the same configuration as in Example 1 was prepared except that a capacitor element having no through hole was used in the capacitor element in Example 1.

  With respect to the case mold type capacitors of Example 1 and Comparative Example 1, noise in a frequency region of 8 to 12 kHz when a ripple current of 50 A was applied was measured. The measurement results are shown in FIG. In addition, about the measurement of a noise, it measured in the position 100 mm away from the wide surface of the case.

  As is apparent from FIG. 3, the case mold type capacitor of the present embodiment is 10 to 20 dB lower than the comparative example in the frequency range of 9 to 11 kHz.

  As described above, in the case mold type capacitor according to the present embodiment, the capacitor element 11 has the through hole 13 at the center of the oval flat surface, and the through hole 13 is filled with the mold resin. In addition, since the metallized film in the through-hole 13 is fixed by the mold resin, even if a current flows through the capacitor element 11 and Lorentz force is generated between the metallized films, the metallized film Vibration can be suppressed. As a result, the vibration of the capacitor element 11 is reduced, and the generation of noise in the case mold type capacitor is suppressed.

  The case mold type capacitor according to the present invention suppresses vibration resistance at a working voltage and satisfies a large capacity performance when a plurality of capacitors are accommodated in one case and resin molded. This is useful for smoothing an inverter circuit for driving a motor of an automobile.

DESCRIPTION OF SYMBOLS 11 Capacitor element 12 Electrode 13 Through-hole 14 P pole bus bar 14a Electrode connection part 14b External connection terminal part 15 N pole bus bar 15b External connection terminal part 16 Case

Claims (3)

A case having an opening on the upper surface;
A capacitor element housed in the case and having a pair of electrodes;
A pair of bus bars each having an external connection terminal by connecting an electrode connection to the pair of electrodes of the capacitor element;
In a case mold type capacitor provided with a mold resin filled in the case,
The capacitor element has a cylindrical through hole in the peripheral surface, the case mold type capacitor with an organic resin in the cylindrical through hole is characterized in that it is filled. 2. The case mold type capacitor according to claim 1, wherein the capacitor element has an oval shape, and the through hole is provided at a center portion of an oval flat plane. The capacitor element is formed of a metallized film in which a metal deposition electrode is formed on a dielectric film,
2. The case mold type capacitor according to claim 1, wherein the organic resin filled in the cylindrical through hole is the same type of resin as the material of the dielectric film.

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