JPH04372107A - Metallized film capacitor - Google Patents

Abstract

PURPOSE:To provide a metallized film capacitor which is free from danger of ignition or explosion and is easy of manufacture with simple structure. CONSTITUTION:In a metallized film capacitor 64 which has a rolled metallized film member 30 which is made by putting a pair of metallized films 14 and 20, where the surfaces of dielectric films 10 and 16 are covered, respectively, with electrode metals 12 and 18, on top of the other, and rolling these, a safety belt 34, where first copper foil 40 connected to a first outer electrode 52 and a second copper foil 44 connected to a second outer electrode 56 are counterposed with an insulating film 36, which fuses at a specified temperature or more, between, is wound on the periphery 46 of the rolled metallized film member 30.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metallized film capacitor, and more particularly to a metallized film capacitor that can reliably operate external safety devices and prevent dangers such as fire and explosion in the event of ultimate destruction.

0002

[Prior Art] Conventionally, capacitors using a wound metallized film member, which is constructed by winding a thin dielectric film on which electrode metal is vapor-deposited, are re-insulated even if a partial dielectric breakdown occurs in the dielectric film. Due to its excellent self-healing properties, it is widely used in various electrical and electronic devices, including household electrical appliances.

[0003] Even metallized film capacitors with these excellent characteristics are subject to repeated application of abnormal surge voltages,
When used for a long period of time, the frequency of partial dielectric breakdown increases due to the deterioration of the dielectric film, and the deterioration is further accelerated by the partial discharge and temperature rise accompanying dielectric breakdown, and finally short-circuit breakdown occurs. This will lead to.

However, even in this state, the metallized film capacitor does not completely short-circuit due to the above-mentioned self-recovery function, and usually has a resistance of several tens of ohms to several tens of kilohms, depending on the thickness of the dielectric film. The value remains. The short circuit current is limited due to the residual resistance of the dielectric film,
Since the operating current of an externally connected safety device such as a fuse or breaker is not reached, the safety device is not activated and power continues to be supplied to the metallized film capacitor. As a result, the dielectric film is decomposed due to repeated partial discharges and abnormal temperature rises, generating flammable gas, which poses a risk of ignition or explosion.

[0005] Various countermeasures have conventionally been taken against this, such as those in which the outer case is made into a sealed structure and equipped with a safety mechanism that disconnects the conductive path by utilizing the expansion of the case due to gas pressure; Alternatively, devices have been proposed that incorporate a safety mechanism that detects abnormal current, temperature, or generated gas and cuts off power supply.

[0006]

[Problems to be Solved by the Invention] However, in the conventional capacitor with a safety mechanism described above, the structure of the safety mechanism is complicated, the manufacturing work is complicated, the manufacturing cost is high, and the external size is increased. There was a problem.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a metallized film capacitor which is free from the risk of fire or explosion, and which has a simple structure and is easy to manufacture.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the metallized film capacitor according to the present invention comprises a pair of metallized films in which electrode metal is deposited on the surface of a dielectric film, and In a metallized film capacitor having a wound metallized film member formed by laminating and winding this, on the outer periphery of the wound metallized film member,
A first metal foil connected to the first external electrode and a second metal foil connected to the second external electrode are sandwiched between an insulating film that melts at a predetermined temperature or higher. It was configured so that safety belts placed facing each other were wrapped around it. The first metal foil and the second metal foil are preferably made of copper foil, for example.

[0009] Note that an adhesive is applied to one side of the safety belt, and the adhesive-coated surface of the safety belt is tightly wrapped around the outer periphery of the rolled metallized film member. It may be configured such that the end portion of the winding is stopped.

[0010] Furthermore, in a metallized film capacitor having a wound metallized film member formed by laminating and winding a pair of metallized films each having an electrode metal deposited on the surface of a dielectric film, the above-described metallized film capacitor is provided. During the winding of the metallized film, a first metal foil with good conductivity is connected to the first external electrode, and a second metal foil is connected to the second external electrode.
It may also be configured such that a safety belt is wrapped around the well-conducting metal foil and a safety belt placed facing each other with an insulating film that melts at a predetermined temperature or higher sandwiched therebetween.

[0011]

[Function] If an abnormal temperature rise occurs inside the wound metallized film member constituting the metallized film capacitor, the insulating film constituting the safety belt will be affected by the occurrence of the abnormal temperature. The first and second highly conductive metal foils are melted at corresponding locations, and the first and second highly conductive metal foils come into contact with each other. As a result, a complete electrical short circuit occurs between the first external electrode and the second external electrode.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the illustrated embodiments. The metallized film capacitor according to this example is
As shown in FIG. 1, a tape-shaped first dielectric film 10 made of synthetic resin such as polyester or polypropylene
A first metallized film 14 with a first electrode metal 12 formed on one side thereof, and a second metallized film 14 formed on one side of a second dielectric film 16 with a first electrode metal 12 formed thereon.
a second metallized film 20 on which an electrode metal 18 is formed.

The first electrode metal 12 and the second electrode metal 18 are both formed by depositing a metal such as aluminum or zinc on the surfaces of the first dielectric film 10 and the second dielectric film 16 by means of vapor deposition or the like. The first
The electrode metal 12 is formed on the top surface of the first dielectric film 10 leaving a first margin part (non-electrode formation part) 24, and the second electrode metal 18 is formed on the top surface of the second dielectric film 16. A second margin portion 28 is left. These first metallized film 14 and second metallized film 20
The rolled metallized film member 30 is formed by overlapping and laminating and winding.

The end portion 32 of the wound metallized film member 30 is shown in FIG. 2 and FIG.
The first safety belt 34 shown in FIG. That is, the first safety belt 34 is formed by attaching the first copper foil 40 to the upper surface of the tape-shaped first insulating film 36, leaving the third margin part 38, and 36, by leaving a fourth margin portion 42 and depositing a second copper foil 44 on the lower surface. 1st above
The insulating film 36 is the first dielectric film 10
It has substantially the same width as the second dielectric film 16, and is made of a material with a relatively low melting point (eg, polyethylene, polystyrene, etc.).

Then, an adhesive is applied to the surface of the first copper foil 40 of the first security belt 34, and the adhesive-applied surface is attached to the rolled metallized film member 30, as shown in FIG. By closely contacting the wound metallized film member 30 and wrapping the first security belt 34 along the outer circumferential surface 46 of the wound metallized film member 30, the winding end portion 3 of the wound metallized film member 30 is closed, as shown in FIG.
2 is wound. As a result of the above, a metallized film capacitor element 48 is formed.

After the metallized film capacitor element 48 formed as described above is subjected to heat and pressure treatment, as shown in FIG. The first external electrode 52 is formed. Similarly, the second winding end face 54 of the metallized film capacitor element 48 is also coated with metallization to form a second external electrode 56. A first external terminal 60 and a second external terminal 62 are connected to the first external electrode 52 and the second external electrode 56 by solder 58, respectively. As a result, the metallized film capacitor 64 according to this embodiment is completed.

FIG. 7 shows the metallized film capacitor 64.
FIG. 3 is a partial cross-sectional view showing the internal stacked state. As shown in the figure, the first safety belt 34 is in close contact with the top layer of the first dielectric film 10 and the second dielectric film 16 that are laminated in multiple layers. The left end portion 66 of the first electrode metal 12 is in contact with the first external electrode 52, but the right end portion 68 is separated by the first margin portion 24, so that the second external electrode 56 has not been in contact with. Further, the right end portion 70 of the second electrode metal 18
However, since its left end portion 72 is separated by the second margin portion 28, it is not in contact with the first external electrode 52.

The first copper foil 40 of the first security belt 34 has its left end 74 in contact with the first external electrode 52;
Since the right end portion 76 is separated by the third margin portion 38, it does not contact the second external electrode 56. Conversely,
The right end 78 of the second copper foil 44 is connected to the second external electrode 5.
6, but the left end portion 80 is in contact with the fourth margin portion 4
2, so it does not contact the first external electrode 52.

In the metallized film capacitor 64 having the above configuration, the first insulation of the first safety belt 34 is The film 36 also maintains its original shape and maintains the insulation state between the first copper foil 40 and the second copper foil 44.

On the other hand, if an abnormality occurs inside the metallized film capacitor 64 and the temperature of a part of the wound metallized film member 30 rises, the temperature of the first insulating film 36 of the first security belt 34 increases. The corresponding locations are melted, and the first copper foil 40 and the second copper foil 44 come into contact at that location. As a result, the first external electrode 52 and the second external electrode 56 are completely short-circuited. When such a short circuit occurs, an externally connected current fuse or breaker operates to cut off the power supply to the metallized film capacitor 64, thereby preventing ignition, explosion, etc.

In this embodiment, as described above, the first security belt 34 also serves as a sealing tape for wrapping the wound metallized film member 30, so that the manufacturing process can be simplified.

In the above embodiment, the first security belt 34
1 along the outer peripheral surface 46 of the metallized film member 30
Although an example in which the first security belt 34 is wound is shown, the first security belt 34 may be wound around the outer circumferential surface 46 of the wound metallized film member 30 multiple times. However, in this case, it is necessary to use the second security belt 82 shown in FIG. 8 and FIG. 9 which is a BB sectional view of FIG. 8. The second safety belt 82 is the same as the first safety belt 3.
4, the first copper foil 40 and the first insulating film 36
and the second copper foil 44 as a basis, and further the second copper foil 4
4, a second insulating film 84 is disposed on the lower surface of the second insulating film 84.

[0023] In this way, the second copper foil 44 has a second
Since the insulating film 84 is arranged, even if it is wrapped multiple times along the outer peripheral surface 46 of the wound metallized film member 30,
The first copper foil 40 and the second copper foil 44 do not come into direct contact with each other, and can maintain an insulated state between them.

FIG. 10 shows a partial sectional view of the second safety belt 82 wound twice around the outer peripheral surface 46 of the wound metallized film member 30. As illustrated, the first copper foil 40 and the second copper foil 44 of the second safety belt 82 are separated by the first insulating film 36 and the second insulating film 84. If there is an abnormal temperature rise somewhere inside the rolled metallized film member 30, the first insulating film 36 and the second insulating film 84 will melt at the corresponding location, and the first insulating film 36 and the second insulating film 84 will melt at the corresponding location. Copper foil 40 and second copper foil 44 are in contact.

When winding the second safety belt 82, an adhesive is applied to the surface of the first copper foil 40 in the same manner as described above, and the rolled metallized film member 30 is wrapped with the adhesive. The second security belt 82 may be configured so as to be unwound, or may be configured to be unwound at the end of the winding of the second security belt 82 using a separate seal tape.

[0026] In the above embodiment, an example was shown in which the second security belt 82 was wrapped around the outer peripheral surface 46 of the wound metallized film member 30, but the present invention is not limited to this.
Although not shown, the first metallized film 14 and the second metallized film 20 may be wound together during the winding of the rolled metallized film member 30. Even in this case, if there is an abnormal temperature rise somewhere inside the rolled metalized film member 30, the first
The insulating film 36 and the second insulating film 84 are melted, and the first copper foil 40 and the second copper foil 44 are brought into contact.

In each of the above embodiments, the first copper foil 40 and the second copper foil 44 were used as the first and second conductive metal foils, respectively. The material is not limited to this, and any metal foil with a low resistance value may be used.

[0028]

Effects of the Invention The metallized film capacitor according to the present invention is configured such that the security belt is wound around the outer periphery of the wound metallized film member or wound inside the wound metallized film member. When an abnormal temperature rise occurs inside the thermoplastic film member, the heat generation melts the insulating film constituting the safety belt, causing the first and second conductive metal foils to come into contact with each other. do. Therefore, the first external electrode and the second external electrode are completely short-circuited, and the externally connected safety devices such as current fuses and breakers operate reliably to cut off the power supply to the metallized film capacitor. Ignition, explosion, etc. can be prevented.

The security belt can also be used as a seal tape by applying an adhesive to one side of the safety belt and configuring the security belt to wrap the end of the wound metallized film member. , the manufacturing process can be simplified.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a rolled metallized film member according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a first safety belt according to the above embodiment.

[Fig. 3] Fig. 2A- showing the first safety belt according to the above embodiment.
It is an A sectional view.

FIG. 4 is a side view showing the rolled metallized film member and the first security belt according to the above embodiment.

FIG. 5 is a side view showing the rolled metallized film member and the first security belt according to the above embodiment.

FIG. 6 is a perspective view showing the metallized film capacitor according to the above example.

FIG. 7 is a partial cross-sectional view of the above embodiment.

FIG. 8 is a perspective view showing a second safety belt according to another embodiment of the present invention.

FIG. 9 is FIG. 8B- showing the second safety belt according to the above embodiment.
It is a sectional view of B.

FIG. 10 is a partial sectional view of the above embodiment.

[Explanation of symbols]

10 First dielectric film 12 First electrode metal 14 First metallized film 16 Second dielectric film 18 Second electrode metal 20 Second metallized film 30 Rolled metallized film member 32 End of winding 34 First safety belt 36 First insulation film 40 First copper foil 44 Second copper foil 46 Outer surface 52 First external electrode 56 Second external electrode 64 Metallized film capacitor 82 Second security belt 84 Second insulation film

Claims (3)

[Claims] 1. A metallized film capacitor having a wound metallized film member formed by laminating and winding a pair of metallized films each having an electrode metal deposited on the surface of a dielectric film, the above-mentioned a first external electrode connected to the first external electrode on the outer periphery of the wound metallized film member;
and a second good conductive metal foil connected to the second external electrode are wrapped with a safety belt that is placed facing each other with an insulating film that melts at a predetermined temperature or higher sandwiched therebetween. metallized film capacitor. Claim 2: Applying adhesive to one side of the security belt,
2. The metal according to claim 1, wherein the adhesive coated surface of the security belt is tightly wound around the outer periphery of the wound metallized film member, thereby stopping the winding end portion of the wound metallized film member. film capacitor. 3. A metallized film capacitor having a wound metallized film member formed by laminating and winding a pair of metallized films each having an electrode metal deposited on the surface of a dielectric film, the above-mentioned In the middle of winding the metallized film, a first electrode is connected to the first external electrode.
and a second good conductive metal foil connected to the second external electrode are wrapped together with a safety belt placed facing each other with an insulating film that melts at a predetermined temperature or higher sandwiched therebetween. A metallized film capacitor featuring: