JP6937250B2 - Capacitor - Google Patents

Description

The present invention relates to a capacitor, and particularly to a capacitor that can effectively cope with an overvoltage applied.

Conventionally, a winding type capacitor element in which an electrode foil (anode foil and cathode foil) having a lead tab connected to the surface is wound with an electrolytic paper (separator) sandwiched between them is impregnated with an electrolytic solution and sealed in an outer case. In an electrolytic capacitor, when an abnormal stress such as an overvoltage is applied, the capacitor element generates heat due to an increase in leakage current and becomes high in temperature, and the pressure inside the case rises due to the vaporization of the electrolytic solution and the electrode foil expands due to the high temperature. Since the electrolytic paper is compressed by the pressure rise in the case and the expansion of the electrode foil, the distance between the poles of the anode foil and the cathode foil, especially the distance between the lead tab and the electrode foil, becomes short, causing a short circuit or a capacitor element. The winding core of the coil bends in a dogleg shape in the direction of the winding axis, causing a short circuit, and even greater electrical energy concentrates on the short circuit area, causing the outer case to be destroyed. was there.

As one measure for solving such a problem, for example, a structure for preventing a short circuit between the anode foil and the cathode foil has been considered (see Patent Document 1).

Japanese Unexamined Patent Publication No. 11-16788

However, the above-mentioned conventional configuration does not completely prevent a short circuit when an excessive abnormal stress such as an overvoltage occurs, and it may be difficult to prevent a short circuit itself depending on excessive conditions. rice field.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a capacitor capable of effectively responding to the occurrence of an abnormality by limiting the damaged portion caused by the occurrence of the abnormal stress.

The capacitor of the present invention houses a capacitor element in which lead tabs are connected to each of the anode foil and the cathode foil, and the anode foil and the cathode foil are wound via a separator, and the capacitor element impregnated with an electrolyte. It includes a bottomed cylindrical outer case, a sealing body having an external terminal that seals the open end of the outer case and is connected to the lead tab, and an insulating member that is inserted into the winding core of the capacitor element. The insulating member has a diameter larger than that of the winding core portion and engages with the winding axis end portion of the capacitor element, and the winding core at a part of the length in the winding axis direction of the capacitor element. The length of the support portion in the winding axis direction of the capacitor element, which has a contact portion that contacts the inner peripheral surface of the portion and a support portion that supports the contact portion at a predetermined distance from the seat plate. It is characterized in that the position where the contact portion comes into contact with the inner peripheral surface of the winding core portion can be set.

According to this configuration, since the insulating member contacts the inner peripheral surface of the winding core portion in a part of the winding core portion, the location where damage occurs due to a short circuit or the like when an overvoltage is applied is limited to the intended range. can do.

Further, in the capacitor of the present invention, in the above configuration, the insulating member contacts the inner peripheral surface of the winding core portion of the capacitor element in a state of being partially separated from each other in the circumferential direction of the inner peripheral surface. It is characterized by.

According to this configuration, by contacting the inner peripheral surface of the winding core portion and the insulating member in a state of being partially separated from each other in the circumferential direction, the stress generated at the contact portion can be set by the size of the contact surface. Can be. As a result, the stress generated in the contact portion can be set by simply changing the contact width of the insulating member in the circumferential direction with respect to the winding core portion without changing the length in the insertion direction of the insulating member with respect to the winding core portion. It is possible to set the susceptibility to a short circuit at a damaged portion in the axial direction of the element without changing the damaged portion.
Further, the capacitor of the present invention is characterized in that, in the above configuration, an exterior member that covers the outside of the exterior case is further provided, and the exterior member is partially provided on the exterior case according to the position of the insulating member. do.

According to the capacitor of the present invention, it is possible to provide a capacitor capable of effectively responding to the occurrence of an abnormality by limiting the damaged portion caused by the occurrence of the abnormal stress.

It is a top view and the cross-sectional view which shows the structure of the electrolytic capacitor which concerns on embodiment of this invention. It is a perspective view which shows the capacitor element which concerns on embodiment of this invention. It is a perspective view which shows the structure of the pin which concerns on embodiment of this invention. It is a side view which shows the structure of the pin which concerns on embodiment of this invention. It is sectional drawing which shows the cross section of the pin which concerns on embodiment of this invention. It is sectional drawing which shows the cross section of the pin which concerns on embodiment of this invention. It is a schematic diagram which provides the description at the time of applying the overvoltage of the capacitor element which concerns on embodiment of this invention. It is a side view which provides the explanation of the exterior member which concerns on embodiment of this invention. It is a schematic diagram which shows the structure of the pin which concerns on other embodiment. It is a schematic diagram which shows the structure of the pin which concerns on other embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIG. 1, the electrolytic capacitor 1 according to the embodiment of the present invention includes a capacitor element 2, a case (exterior case) 3a, a sealing body 3b, a bottom plate 4, a sleeve 5, a fixing material 6, and a terminal (external terminal) 7a. , 7b and pressure valve 10, pin 20.

The case 3a accommodates the capacitor element 2, and the sealing body 3b is fitted in the opening. The sealing body 3b seals the case 3a. The case 3a is made of a metal (aluminum or the like), and the sealing body 3b is made of an insulating material (modified phenol resin or the like).

A packing 3x made of an elastic material (rubber or the like) is provided on the upper peripheral edge of the sealing body 3b. The packing 3x has a function of preventing the gas in the case 3a from leaking from the gap between the sealing body 3b and the case 3a. The packing 3x is crimped and fixed at the upper end of the case 3a.

The bottom plate 4 is a circular film made of an insulating material (flame-retardant polyester or the like), and is arranged so as to overlap the lower surface of the bottom portion of the case 3a. The sleeve 5 is a substantially cylindrical member made of an insulating material (polyolefin or the like), and covers the side peripheral surface of the case 3a, the lower peripheral edge of the bottom plate 4, and the upper peripheral edge of the case 3a. The lower part of the sleeve 5 is fixed to the bottom plate 4.

The fixing material 6 fixes the capacitor element 2 in the case 3a, and is made of a thermoplastic resin (polypropylene or the like).

The terminals 7a and 7b and the pressure valve 10 are provided on the sealing body 3b. The terminals 7a and 7b are provided at positions that are point-symmetrical with respect to the center of the sealing body 3b when viewed from the thickness direction of the sealing body 3b, and are separated from each other. The terminals 7a and 7b are made of metal (aluminum or the like), the cathode terminal 7a is connected to the cathode lead tab 2a of the capacitor element 2, and the anode terminal 7b is connected to the anode lead tab 2b of the capacitor element 2.

The sealing body 3b is formed with a through hole 3b1 that communicates the inside and the outside of the case 3a between the center (center between the terminals 7a and 7b) and the outer edge when viewed from the thickness direction of the sealing body 3b. ing. The pressure valve 10 is provided so as to close the through hole 3b1, and is fixed to the sealing body 3b by a lock washer 8 provided on the upper surface thereof. The pressure valve 10 has a function of discharging the gas in the case 3a.

Next, the configuration of the capacitor element 2 will be described in detail with reference to FIG.

The capacitor element 2 is formed by winding a cathode foil 2x and an anode foil 2y to which a cathode lead tab 2a and an anode lead tab 2b are attached, respectively, via a separator (kraft paper or the like) 2z made of an insulating material. It is formed by fixing the outer periphery of the body with an element fixing tape 2t and then impregnating the winding body with a driving electrolytic solution. The cathode foil 2x and the anode foil 2y have roughened surfaces of the aluminum foil, and the anode foil 2y has an anodized film formed on the surfaces.

Here, in the manufacturing process of the capacitor element 2, the cathode foil 2x, the anode foil 2y and the separator 2z are wound around the core member and then pulled out from the cathode foil 2x, the anode foil 2y and the separator 2z. The winding body 15 is formed, and a cavity remains in the central portion (winding core portion) of the winding body 15 after the winding core member is pulled out.

In the electrolytic capacitor 1 of the present embodiment, by inserting the pin 20 into the cavity 15a from the sealing body 3b side, the winding body 15 (cavity 15a) can be formed in a predetermined range on the sealing body 3b side of the cavity 15a. A contact portion is formed between the inner peripheral surface 15b and the pin 20.

3 and 4 are perspective views and side views of the pin 20, and FIGS. 5 and 6 are cross-sectional views showing the line AA of FIG. 4 in cross section.

As shown in FIG. 3, the pin 20 is formed entirely of a resin material and has a diameter larger than the diameter of the core portion (cavity portion 15a) of the winding body 15, and the winding shaft of the pin 20 with respect to the cavity portion 15a. It has a disk-shaped seat plate 21 that functions as a directional positioning means, and a protrusion 22 formed on one surface of the seat plate 21. The protrusions 22 are formed with four contact portions 25, 26, 27 and 28 radially in a direction orthogonal to the longitudinal direction, which is the insertion direction into the cavity portion 15a.

In the abutting portions 25 to 28, the abutting surfaces 25a, 26a, 27a and 28a have a shape substantially following the shape of the inner peripheral surface 15b of the cavity portion 15a of the winding body 15, and the abutting portions 25 to 28. The outer diameter shape of the 28 (distance between the contact surfaces 25a and 27a, the distance between the front end surfaces 26a and 28a) is substantially the same as the diameter of the cavity portion 15a. As a result, when the pin 20 is inserted into the cavity portion 15a, the contact surfaces 25a to 28a of the contact portions 25 to 28 and the inner peripheral surface 15b of the cavity portion 15a form an electrode foil (a winding body 15). The cathode foil 2x and the anode foil 2y) are contacted at a contact pressure such that a short circuit does not occur under a normal state in which an overvoltage is not applied.

Further, in the tip portion of the protrusion 22, tapered surfaces 25b, 26b, 27b and 28b are formed on the contact portions 25 to 28, and the shape is tapered toward the tip. As a result, when the protrusion 22 is inserted into the cavity 15a from the tip portion, it can be smoothly inserted and the wound body 15 can be prevented from being scratched.

As shown in FIG. 5, in the protrusion 22, the contact portions 25, 26, 27 and 28 are chamfered so that both end portions 25c, 26c, 27c and 28c of the contact surfaces 25a, 26a, 27a and 28a are curved. Has been done. With such a shape, as compared with the case where the both end portions 25c, 26c, 27c and 28c are formed at an acute angle, the cavity 22 is inserted into the cavity portion 15a as shown in FIG. It is possible to prevent the inner peripheral surface 15b of the portion 15a from being scratched.

Here, at the contact surfaces 25a to 28a of the contact portions 25 to 28, the total width W1 (FIG. 5) in the circumferential direction is the diameter of the cavity portion 15a (FIG. 2) (winding of the winding body 15). It is formed so as to be 20 to 40% of the diameter of the core portion). The reason is that if it is less than 20%, the contact area between the contact surfaces 25a to 28a and the inner peripheral surface 15b of the cavity portion 15a becomes small, so that the stress generated at the contact portion becomes too small. This is because if it exceeds%, the stress generated at the contact portion becomes too large. Specifically, as shown in FIG. 7, when the volume of the winding body 15 becomes large when an overvoltage is applied, a part of the inner peripheral surface 15b of the cavity portion 15a of the winding body 15 is inside (winding shaft side). ), A “dogleg” -shaped deformed portion 15c is generated. When an overvoltage is applied while the protrusion 22 of the pin 20 is inserted into the cavity 15a, the contact surfaces 25a to 28a of the contact portions 25 to 28 come into contact with the inner peripheral surface 15b at the deformed portion 15c. The stress on the electrode foils (cathode foil 2x, anode foil 2y) increases depending on the portion, but the total width W1 (FIG. 5) of each of the contact surfaces 25a to 28a in the circumferential direction is the cavity portion 15a (FIG. 2). If it is less than 20% of the diameter, the electrode foils (anode foil 2x, anode foil 2y) between the abutting portions are deformed so as to protrude inward, and the electrode foils (anode foils) facing the abutting surfaces 25a to 28a occur. The stress on the foil 2x, the anode foil 2y) becomes weaker, and the electrode foil (cathode foil 2x, This is because there is a high possibility that a short circuit will occur in the anode foil 2y), whereas if it exceeds 40%, the stress will be too large, the overvoltage resistance performance will be lowered, and a short circuit will be likely to occur.

Further, in each of the contact surfaces 25a to 28a of the contact portions 25 to 28, the length L1 (FIG. 4) in the longitudinal direction (insertion direction of the cavity portion 15a into which the protrusion 22 is inserted) is set to 15 to 30 mm. It is preferable to do so. The reason is that when the thickness is less than 15 mm, the contact area between the contact surfaces 25a to 28a and the inner peripheral surface 15b of the cavity 15a becomes small, so that the volume of the winding body 15 becomes large as described above with respect to FIG. In this case, the stress applied to the electrode foils (cathode foil 2x, anode foil 2y) near the cavity 15a becomes weaker, and the contact surfaces 25a to 28a of the contact portions 25 to 28 come into contact with the inner peripheral surface 15b of the cavity 15a. There is a high possibility that a short circuit will occur in the electrode foil (cathode foil 2x, anode foil 2y) other than the portion where the electrode foil (cathode foil 2x, anode foil 2y) is short-circuited. This is because the overvoltage performance is lowered and a short circuit is likely to occur.

The electrolytic capacitor 1 and the pin 20 manufactured in a state where the pin 20 having the contact portions 25 to 28 having such a configuration is inserted into the cavity portion 15a of the winding body 15 from the sealing body 3b side are provided. A test was conducted in which an overvoltage was applied to an electrolytic capacitor that did not exist, and short circuits were confirmed.

Specifically, it is a screw terminal type aluminum electrolytic capacitor (external dimensions: diameter φ90 mm × length 220 mm) with a rating of 400 V / 18000 μF, and the dimensions of the capacitor element are diameter φ83 mm × length 200 mm, and the winding core of the winding body 15. The test was performed on a portion (cavity portion 15a) having a diameter of φ10 mm, with an applied voltage of 800 V, a test current of 10 A, and a test temperature of room temperature.

As a result, in the conventional product not provided with the pin 20, a short circuit occurred in 4 out of 5 samples. As for the short-circuited parts, three were generated at the bottom (bottom side of the case) of the capacitor element, and one was generated at the center (the central part between the bottom side of the case and the sealing body side). ..

On the other hand, in the configuration of the present embodiment including the pins 20, short circuits occur in 5 out of 5 samples, and the short circuit locations are all in the vicinity of the contact portions 25 to 28 of the pins 20. ..

From this test result, it was found that in the electrolytic capacitor 1 provided with the pin 20, the position where the short circuit occurs is limited depending on the position where the pin 20 is inserted. That is, it was found that by providing the pin 20, it is possible to limit the position where the short circuit occurs.

Specifically, as shown in FIG. 7, when an overvoltage is applied to the capacitor element 2, the leakage current suddenly increases, causing heat generation and expansion of the electrode foil in the capacitor element 2. The heat generated by the capacitor element vaporizes the electrolytic solution and raises the pressure inside the case. When the pin 20 is not inserted into the cavity 15a, the element is deformed toward the cavity 15a due to the pressure increase and expansion (deformation portion 15c). In the capacitor element 2 of the present embodiment, since the protrusion 22 of the pin 20 is inserted into the cavity 15a, the contact pressure between the deformed portion 15c and the protrusion 22 (contact surfaces 25a to 28a) is large. Therefore, the stress generated in this contact portion can be made larger than that in the portion where the protrusions 22 (contact surfaces 25a to 28a) of the pin 20 are not in contact with the inner peripheral surface 15b of the cavity portion 15a. As a result, a short circuit can be intentionally induced in the contact portion, and the short circuit portion can be limited to the intended portion.

Therefore, for example, as shown in FIG. 8, in the configuration in which the pin 20 is inserted from the sealing body 3b side into the cavity portion 15a of the winding body 15, the periphery of the portion where the pin 20 is inserted (that is, the electrolytic capacitor) By covering (around the sealing body 3b side of 1) with, for example, a high-strength exterior member 40 made of a metal material, even if a short circuit occurs due to an overvoltage state and the case 3a is damaged. It is possible to prevent the damaged object from scattering to the surroundings only by partially providing the exterior member 40. That is, it is possible to deal with a case where an abnormality such as a short circuit occurs in the electrolytic capacitor 1 by a simple configuration without using a large-scale configuration in which the entire electrolytic capacitor is covered with a high-strength exterior member.

The position where the exterior member 40 is provided may be provided not only at a position facing the outer peripheral surface of the case of the electrolytic capacitor 1 as shown in FIG. 8 but also at a position facing the upper surface where the sealing body 3b is provided. good. Further, the exterior member 40 may be provided so as to be in contact with the electrolytic capacitor 1, or may be provided so as to be separated from each other as shown in FIG.

In the above configuration, for example, when two electrolytic capacitors with a rating of 400V are connected in series and used at 800V, 400V is applied to each electrolytic capacitor if no abnormality occurs, but one of the electrolytic capacitors is electrolyzed. When the capacitor fails and becomes conductive, 800V is applied to the other electrolytic capacitor, and the electrolytic capacitor is in a state where an overvoltage is applied. Even in this case, by providing the electrolytic capacitor with the pin 20, it is possible to limit the location where damage occurs due to a short circuit or the like when an overvoltage is applied to an intended range. As a result, even if there are restrictions on the position where the high-strength exterior member 40 (FIG. 8) is provided depending on the layout in which the electrolytic capacitor is provided, the location where the electrolytic capacitor is damaged due to an abnormality such as a short circuit depending on the position of the exterior member 40. Can be aligned with the position of the exterior member 40.

Further, according to the above configuration, it is possible to limit the damaged part due to a short circuit or the like only by inserting the pin 20 into the cavity portion 15a formed in the winding core portion of the capacitor element 2. The configuration according to the invention can be easily introduced.

In the above-described embodiment, the configuration in which the pin 20 is inserted into the cavity portion 15a of the winding body 15 from the sealing body 3b side is described, but the present invention is not limited to this, and for example, the case 3a. It may be inserted from the bottom side. In this case, by providing the exterior member 40 in a limited range around the bottom of the case 3a, it is possible to deal with damage when a short circuit occurs.

Further, in the above-described embodiment, by using the pin 20 in which the protrusion 22 is directly formed on the seat plate 21 as the positioning means for the cavity 15a of the winding body 15, the upper portion of the cavity 15a (sealing body 3b side) is used. ) Or the lower portion (the bottom side of the case 3a), the protrusion 22 (contact portion 25 to 28) is provided, but the present invention is not limited to this, and the central portion (electrolysis) of the capacitor element 2 in the length direction is provided. It may be provided at a substantially central portion between the sealing body 3b side of the capacitor 1 and the bottom side of the case 3a). FIG. 9 is a diagram showing an embodiment in which the contact portions 25 to 28 are arranged in the central portion of the cavity portion 15a, which are shown by assigning the same reference numerals to the portions corresponding to those in FIGS. 3 to 5.

As shown in FIG. 9, the pin 120 has contact portions 125, 126, 127 and 128 that come into contact with the inner peripheral surface 15b of the winding body 15. These abutting portions 125 to 128 are provided radially in the same manner as the abutting portions 25 to 28 of the pin 20 described above. Since the contact portion 127 is provided in the depth direction of the paper surface in FIG. 9, only the reference numerals are shown.

In the contact portions 125 to 128, the contact surfaces 125a, 126a, 127a and 128a are the inner peripheral surfaces of the winding body 15, similarly to the contact portions 25 to 28 of the pins 20 described in FIGS. 3 to 8. It is configured to come into contact with 15b and induce a short circuit when an overvoltage is applied at the contact portion.

Since it is necessary to insert the contact portion 125-128 deeply into the cavity portion 15a of the winding body 15, the pin 120 has the contact portion 125-128 at a predetermined distance from the seat plate 21 by the columnar support portion 123. Is configured to support. The contact position between the contact portion 125 to 128 and the inner peripheral surface 15b of the winding body 15 can be determined by the length of the support portion 123. Therefore, by using the support portion 123 having a length corresponding to the position where the short circuit is to be induced when the overvoltage is applied, the short circuit is induced at an appropriate position according to the position where the exterior member 40 (FIG. 8) is arranged. be able to.

In the pin 120 shown in FIG. 9, since it is necessary to insert the contact portion 125-128 into the cavity portion 15b of the winding body 15a deeper than the length of the contact portion 125-128, the winding Tapered surfaces 125b, 126b, 127b, and 128b are formed on both upper and lower ends of the contact surfaces 125a to 128a that come into contact with the inner peripheral surface 15b of the body 15. As a result, it is possible to prevent the inner peripheral surface 15b of the winding body 15 from being scratched by the abutting portions 125 to 128 when the pin 120 is pulled out from the cavity portion 15a as needed.

Further, in the above-described embodiment, the case where four contact portions 25 to 28 and 125 to 128 are provided on the pins 20 and 120, respectively, has been described, but the present invention is not limited to this, and the number of contact portions may vary. Can be applied. It is preferable to provide 3 to 5 contact portions.

Further, in the above-described embodiment, the configuration in which the pins 20 and 120 are positioned by the seat plate 21 has been described, but the present invention is not limited to this, and for example, as shown in FIG. The protrusion 22 may be fixed to the body 3b. That is, in FIG. 10 in which the corresponding portions corresponding to those in FIG. 8 are designated by the same reference numerals, the protrusions 22 are supported on the sealing body 3b via the columnar support portions 50. The protrusions 22 are provided with contact portions 25 to 28 having the same configurations as those described above for FIGS. 3 to 6, so that the contact portions 25 to 28 and the inner peripheral surface of the winding body 15 are provided. The contact portion with 15b can induce a short circuit when an overvoltage is applied.

Even in a configuration in which the sealing portion 3b is provided with the protruding portion 22 via the supporting portion 50, the protruding portion 22 (contact portion 25 to 28) of the winding body 15a can be formed by changing the length of the supporting portion 50. The position of the portion in contact with the inner peripheral surface 15b can be arbitrarily set.

Further, in the above-described embodiment, the case where the pins 20 and 120 formed of the resin material are used has been described, but the present invention is not limited to this, and for example, a metal material whose surface is coated with an insulator is used. , Various materials can be used as long as the contact portion of the winding body 15 with the inner peripheral surface 15b has an insulating property.

1 Electrolytic capacitor 2 Capacitor element 2y Anode foil 2x Cathode foil 2z Separator 3a Case 3b Sealing body 5 Sleeve 15 Winding body 15a Cavity 15b Inner peripheral surface 20, 120 Pin 21 Seat plate 22 Protrusions 25 to 28, 125 to 128 Contact 40 Exterior member

Claims (3)

A capacitor element in which lead tabs are connected to each of the anode foil and the cathode foil, and the anode foil and the cathode foil are wound around the separator.
A bottomed cylindrical exterior case that houses the capacitor element impregnated with electrolyte, and
A sealing body having an external terminal that seals the open end of the outer case and is connected to the lead tab.
It is provided with an insulating member to be inserted into the core portion of the capacitor element.
The insulating member has a diameter larger than that of the winding core portion and engages with the winding axis end portion of the capacitor element, and the winding core at a part of the length in the winding axis direction of the capacitor element. It has a contact portion that contacts the inner peripheral surface of the portion and a support portion that supports the contact portion at a predetermined distance from the seat plate.
A capacitor characterized in that a position where the contact portion contacts the inner peripheral surface of the winding core portion can be set by the length of the support portion in the winding axis direction of the capacitor element. The capacitor according to claim 1, wherein the insulating member contacts the inner peripheral surface of the winding core portion of the capacitor element in a state of being partially and separated from each other in the circumferential direction of the inner peripheral surface. .. An exterior member that covers the outside of the exterior case is further provided.
The capacitor according to claim 1 or 2, wherein the exterior member is partially provided with respect to the exterior case according to the position of the insulating member.

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