JPH0356029Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a case-exposed capacitor in which a metallized film capacitor element is housed in an exterior case and is equipped with a safety device. By connecting this to the capacitor element using a low melting point metal, in the event that the capacitor element eventually breaks down, the power supply to the element can be cut off, preventing dangers such as fire and explosion. The present invention relates to a case-mounted capacitor that can be used.

[Prior art] Conventionally, case-exposed capacitors, in which a metallized film capacitor element is housed in an outer case and filled with a fixing material, have a self-contained structure that recovers insulation properties even if partial dielectric breakdown occurs in the capacitor element. Because of its excellent recovery properties, it is widely used in various electrical and electronic devices, including household electrical appliances.

However, even though metallized film capacitor elements have these excellent characteristics, if abnormal surge voltages are repeatedly applied or if they are used under overloaded conditions for a long period of time, the dielectric that makes up the capacitor element may deteriorate. As the film deteriorates, the frequency of occurrence of partial dielectric breakdown increases, and the partial discharge and temperature rise accompanying the dielectric breakdown further accelerate the deterioration, eventually leading to ultimate breakdown. However, even in this state, the metallized film capacitor element is not completely short-circuited, so external safety devices such as current fuses and breakers cannot fully operate, and power continues to be supplied to the capacitor element. .
As a result, the dielectric film is burnt out due to repeated partial discharges and abnormal temperature rises, generating flammable gas, which poses a risk of the capacitor catching fire or exploding.

As a countermeasure against this problem, case-exposed capacitors have been devised that have various safety devices.For example, the case has a sealed structure and is equipped with a safety device that uses the expansion of the case due to gas pressure to cut the conductive path. There have been proposals for devices incorporating a safety device that detects abnormal current, temperature, or generated gas and shuts off the power supply.

[Problems to be solved by the invention] However, the conventional case-exterior type capacitors mentioned above are equipped with a special safety device, which complicates the structure, complicates manufacturing work, and increases manufacturing costs. There are problems such as an increase in size.

The present invention was devised in view of the above-mentioned points, and aims to provide a case-mounted capacitor that is inexpensive and small, has no risk of fire or explosion, has a simple structure and is easy to manufacture. .

[Means for Solving the Problems] In order to achieve the above object, the present invention forms electrodes on the end face of a metallized film capacitor element to connect external terminals, houses this in an exterior case, and In case-exposed capacitors in which the case is filled with a fixing material and the external terminals are led out of the external case, a space is provided between the external terminals in the external case and the side wall of the external case, and The external terminal was formed of a bimetal, and the side of the bimetal having a larger coefficient of thermal expansion was connected to the electrode with a low melting point metal toward the electrode side of the end face of the capacitor element, and the fixing material was formed of a thermoplastic material. This article focuses on a case-exterior type capacitor that is characterized by the following.

[Function] Since the present invention has the above-described configuration, if the built-in metallized film capacitor element eventually breaks down, the fixing material made of low-melting point metal and thermoplastic material will melt due to the rise in internal temperature. However, the external terminal connected by the low melting point metal separates from the electrode due to the curvature of the bimetal, and moves toward the side wall of the outer case by the distance between it and the side wall of the outer case. Therefore, the external terminal and the electrode are electrically opened, and power supply to the capacitor element is cut off. Further, even if the temperature decreases and the bimetallic external terminal returns to its original position, the external terminal and the electrode will not come into contact again due to the interposition of the fixing material.

[Example 1] Hereinafter, an example of the present invention will be described based on the drawings.

Figure 1 shows one embodiment of the present invention.
Figure A is a schematic sectional view thereof, and Figure 1B is a schematic sectional view showing a state in which the safety device is in operation. In the figure, a case-exterior type capacitor 1 is a metallized film capacitor element 2 made by laminating and winding a metallized film formed by depositing a metal such as aluminum or zinc on a dielectric film made of a synthetic resin such as polyester or polypropylene. is formed, and electrodes 3, 3 are provided by applying metallicon to both end faces thereof. Furthermore, a pair of external terminals 5, 5 attached to the terminal board 4 are connected to the electrodes 3, 3, and a gap is formed between the external terminals 5, 5 and the side wall of the exterior case 6. Exterior case 6 filled with fixing material 7
It has a structure in which the terminal plate 4 is engaged with the outer case 6 and the external terminals 5 are guided out of the outer case 6.

The external terminals 5, 5 are made of a bimetal formed by bonding two types of metals with different coefficients of thermal expansion, such as brass and umber or copper and iron, and the metal with a larger coefficient of thermal expansion is the one described above. It is welded to the electrodes 3, 3 while facing toward the electrodes 3, 3 of the capacitor element 2. In this case, metals with a large coefficient of thermal expansion, such as copper and brass, which are directly connected to the capacitor element have a small electrical resistance, so that the electrical connection characteristics between the capacitor element and the external terminal are also good. Further, the electrodes 3, 3 are formed by thermal spraying a low melting point metal such as low melting point solder, and the metal material is selected according to the operating temperature of the safety device.

The exterior case 6 is made of a heat-resistant synthetic resin such as polyphenylene sulfide or polybutylene terephthalate, and has protrusions 8, 8 formed on the inside of its bottom surface to hold the metallized film capacitor element 2. Further, the terminal plate 4 is made of a heat-resistant insulating material such as phenol, and a partition wall 9 that also serves as a capacitor element holding member is protruded between the external terminals 5 and 5 on the inner surface of the terminal plate 4, and an external part made of molten low-melting point metal is provided. This prevents a short circuit between the terminals 5 and 5.
The protrusions 8, 8 on the bottom of the case and the partition wall 9 on the terminal board
In addition to the above-mentioned function, it also serves to form a gap between the end face of the capacitor element and the exterior case 6, so that no matter what orientation the case-exterior type capacitor 1 is attached to, the melted low melting point The metal accumulates between the end face of the capacitor element 2 and the exterior case 6, and does not come into contact with the end face of the capacitor element and the external terminal again.

The fixing material 7 is made of an insulating thermoplastic material, such as APP, for example, and covers the metallized film capacitor element 2 in a hardened state. The above thermoplastic substances include polyolefin resins such as APP, etc.
Thermoplastic synthetic resins such as polyamide resins, polyester resins, and ester copolymers, wax, paraffin, etc. can be used, and one is selected according to the operating temperature setting of the security device. In this case, the melting temperature of the thermoplastic substance is set to be higher than the operation start temperature of the external terminals 5, 5, that is, the external terminals 5, 5 separate from the electrodes 3, 3 of the metallized film capacitor element 2 due to the curvature of the bimetal. If the temperature is higher than the starting temperature, the external terminal 5,
Even if 5 returns to its original position, the hardening of the thermoplastic material reliably prevents the external terminals 5, 5 from coming into contact with the electrodes 3, 3 again.

[Embodiment 2] Fig. 2 shows another embodiment of the present invention, in which Fig. 2A is a schematic sectional view thereof, and Fig. 2B is a schematic sectional view showing a state in which the safety device is operated. In this embodiment, on both end surfaces of the metallized film capacitor element 2,
The electrodes 3, 3 are formed by spraying a normal metallicon material made of lead with trace elements added, and on these electrodes 3, 3,
Connection member 1 made of low melting point metal such as low temperature solder
External terminals 5 and 5 are connected by terminals 0 and 10. Other structures and operations are substantially the same as in the first embodiment.

In the embodiments described above, a safety device in which the external terminals are made of bimetal and connected with a low-melting point metal is provided on both end faces of the capacitor element, but it may be necessary to In other words, the same effect can be obtained even if it is provided on only one side.

[Effects of the invention] As detailed above, the case exterior type capacitor of the present invention is equipped with a safety device in which the external terminal made of bimetal is connected to the end face of the metallized film capacitor element using a low melting point metal. The heat generated by the eventual destruction of the capacitor element melts the low melting point metal and separates the external terminal from the electrode, thereby cutting off the power supply and reliably preventing ignition or explosion. Furthermore, since the fixing material made of thermoplastic material is filled, there is no fear that the external terminal and the electrode will come into contact again even if the temperature drops. Furthermore, since the above-mentioned safety device can be formed by simply changing the orientation of some of the materials of the ordinary capacitor components, the structure is simple and compact, and it has various practical values such as being easy to manufacture and providing at low cost. It has the following.

[Brief explanation of the drawing]

Fig. 1 shows one embodiment of the present invention, Fig. 1A is a schematic sectional view thereof, Fig. 1B is a schematic sectional view showing the state in which the safety device is activated, and Fig. 2 is another embodiment of the present invention. An example is shown, and FIG. 2A is a schematic sectional view thereof, and FIG. 2B is a schematic sectional view showing a state in which the safety device is operated. DESCRIPTION OF SYMBOLS 1... Case exterior type capacitor, 2... Metallized film capacitor element, 3... Electrode, 5... External terminal, 6... Exterior case, 7... Fixing material, 8...
...Protrusion, 9...Partition wall, 10...Connection member.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) Electrodes are formed on the end face of the metallized film capacitor element and external terminals are connected to it, and this is housed in an exterior case, and the exterior case is filled with a fixing material and the above-mentioned In case-exposed capacitors in which external terminals are led out of the external case, a gap is provided between the external terminals inside the external case and the side wall of the external case, and the external terminals are formed of bimetal. A case-exposed capacitor characterized in that the bimetal having a larger coefficient of thermal expansion is connected to the electrode with a low melting point metal with the side of the bimetal having a larger coefficient of thermal expansion facing toward the electrode side of the end face of the capacitor element, and further comprising a fixing material made of a thermoplastic material. . (2) The case-exterior type capacitor according to claim 1, wherein the electrodes on the end faces of the metallized film capacitor element are formed of a low-melting point metal. (3) The case-exterior type capacitor according to claim 1 of the utility model registration, characterized in that a low melting point metal layer is formed on the electrode on the end face of the metallized film capacitor element. (4) The case-exposed capacitor according to any one of claims 1 to 3, wherein the fixing material has a melting temperature equal to or higher than the operation start temperature of the external terminal. (5) The case-exterior type capacitor according to any one of claims 1 to 4 of the utility model registration claim, characterized in that a space is formed between the end face of the metallized film capacitor element and the exterior case. (6) The case-exterior type capacitor according to any one of claims 1 to 5 of the utility model registration claim, characterized in that a partition wall is formed between external terminals within the exterior case.