JPS6230489B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an exterior case for an electrolytic capacitor, and more particularly to an exterior case that enables improved acoustic characteristics and discharge of gas inside the case. Since the electrolytic capacitor has a polar structure, hydrogen gas is generated from its negative electrode foil, and this generated gas fills the sealed exterior case. This hydrogen gas is generated even when the electrolytic capacitor is used normally, but it is generated especially when a reverse voltage is applied between the electrodes due to reverse polarity connection or when an overvoltage is applied between the electrodes. The amount increases rapidly, causing an abnormal increase in the internal pressure of the outer case. If the internal pressure of the outer case exceeds the allowable stress of the outer case, there is a risk of explosion.
To prevent this, electrolytic capacitors are equipped with gas exhaust devices and explosion-proof devices. Since these means are formed by special processing on the outer case, they require a complicated manufacturing process, and it has been difficult to make their functions uniform. Further, electrolytic capacitors are components of various circuits of audio equipment, and are known to have a subtle influence on the characteristics of the reproduced sound. Moreover, it is considered extremely difficult to electrically measure this effect or analyze the phenomenon. For example, when observing acoustic characteristics with a focus on the exterior case, when comparing and listening to an electrolytic capacitor covered with an aluminum exterior case and an electrolytic capacitor that is not covered with an exterior case, the former seems to have a narrow band of reproduced sound. being exposed to a lot of distortion,
There are drawbacks such as poor separation of individual musical instrument sounds, and it is known that an aluminum exterior case deteriorates the acoustic characteristics. For this reason, it has been proposed to use a synthetic resin exterior case. However, while those made of synthetic resin can provide acoustic properties not found in those made of aluminum, they have the following drawbacks. In other words, synthetic resins have poor adhesion to sealing members made of rubber or the like, and adhesives are required to maintain airtightness.The use of adhesives complicates the manufacturing process, and some of the adhesive may be inside the outer case. If it penetrates, it causes corrosion, and it also has disadvantages such as lower mechanical strength than aluminum and higher manufacturing costs. This invention was made in view of the above points, and a porous alloy material plate of aluminum and tin, mainly made of aluminum, has excellent selective permeability for hydrogen gas and excellent acoustic properties that cannot be obtained with aluminum alone. Based on the knowledge that aluminum has the same characteristics, the present invention aims to provide an exterior case for an electrolytic capacitor that can improve gas discharge characteristics and acoustic characteristics while taking advantage of the plasticity of aluminum. This invention uses a porous alloy material mainly made of aluminum and tin for an exterior case that encloses an electrolytic capacitor element, and in particular,
The content of tin is set at a weight ratio that does not impair the plasticity that allows molding. Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 shows a specific embodiment of the exterior case for an electrolytic capacitor according to the present invention. In the figure, an exterior case 2 formed into a cylindrical shape with a bottom is integrally formed from an aluminum-tin alloy material plate mainly made of aluminum and containing tin. In particular, as a result of the tin content, the outer case 2
The composition is porous. The opening of the exterior case 2 made of this porous alloy material plate is closed with a sealing body 4 made of an elastic material such as rubber. That is, in the vicinity of the opening of the outer case 2, a bulge 6 is formed by press molding over the entire circumference of the outer case 2, and the sealing body 4 is compressed and held by this bulge 6. , an end 8 of the outer case 2 curved and facing the upper surface of the sealing body 4
It is held in the outer case 2 by. The electrolytic capacitor element 10 is enclosed within the thus sealed exterior case 2. As is well known, this electrolytic capacitor element 10 is constructed by winding an anode-side electrode foil and a cathode-side electrode foil with separator paper interposed therebetween, and then impregnating them with an electrolytic solution. Rod-shaped tabs 12A and 12B electrically connected to the anode side electrode foil and the cathode side electrode foil are pulled out from the upper end surface of the electrolytic capacitor element 10, and external lead wires 1
4A and 14B are connected. These rod-shaped tabs 12A, 12B and external lead wires 14A, 14
B penetrates the sealing body 4, a connecting portion between the two is placed inside the sealing body 4, and external lead wires 14A, 14B are drawn out from the upper surface of the sealing body 4. As described above, if an alloy material mainly composed of aluminum containing tin is used for the exterior case 2 of an electrolytic capacitor, the exterior case 2 becomes porous, suppressing evaporation of the electrolyte and allowing only hydrogen gas to pass through. As a result, selective permeability of hydrogen gas is obtained, and hydrogen gas in the outer case 2 can be discharged. Furthermore, the characteristics of each of the external cases 2 produced in large quantities are made uniform. Furthermore, it has been confirmed that since the outer case 2 contains tin, the acoustic characteristics are improved compared to a case made of aluminum. In particular, different acoustic properties can be obtained by changing the tin content,
It has become possible to obtain desired reproduced sound. The reason for this is that the electrical resistance of the exterior case 2 increases due to the inclusion of tin, suppressing the generation of eddy currents due to interlinkage of magnetic lines of force from the electrolytic capacitor element 10, and reducing the generation of secondary magnetic lines of force. It is thought that. In particular, the alloy of tin and aluminum becomes porous as indicated by the gas permeability, and the increase in electrical resistance accompanying the alloying is considered to be useful for improving acoustic properties. Regarding alloys of tin and aluminum, there is a limit to the tin content in terms of forming process. That is, as the amount of tin relative to aluminum increases, the plasticity is lost, and as the properties of tin become stronger, the material becomes softer. Therefore, the tin content should be within a range where the properties of aluminum are not lost and the plasticity that allows molding by press is not lost. Next, the electrolytic capacitor shown in FIG. 2 shows another embodiment of the present invention, and the exterior case of the present invention can be effectively applied to this type of electrolytic capacitor. That is, the sealing body 16 of this electrolytic capacitor uses a hard insulating plate 20 made of Bakelite or the like to which an elastic member 18 such as rubber is attached, and the sealing body 16 is attached to the upper side of the outer case 22 in an inward direction. The outer case 24 is engaged with the bulge 24 formed on the surface of the sealing body 16, and the exterior case 2
Two curved ends 26 are exposed. The sealing body 1 that closes the exterior case 22 in this way
Rivets 28A, 28B are penetrated through the terminals 6, and plate terminals 30A, 30B are provided on the surface of the sealing body 16.
and the flat tabs 34A, 34B of the electrolytic capacitor element 32 drawn out to the back surface of the sealing body 16 are electrically connected together on the sealing body 16 by the rivets 28A, 28B. In this way, the outer case 22 in which the sealing body 16 is supported by the bulging portion 24 also has sufficient plasticity and mechanical strength by adjusting the content of tin, so that the outer case of the present invention can be effectively improved. can be used. Therefore, the exterior case of the present invention can be applied regardless of its shape, sealing structure, or terminal shape, and is not limited to the embodiments. Next, FIGS. 3 to 6 show modified examples of the present invention, and these will be explained below. The electrolytic capacitor shown in Figure 3 is
The above-mentioned porous alloy material plate is used for a part of 6. That is, in this embodiment, the outer case 3
The bottom portion 38 of No. 6 is made of the aluminum-tin alloy. With this configuration, hydrogen gas can be discharged by using the device with the alloyed portion facing upward. If used in the exterior case of an electrolytic capacitor where acoustic characteristics are not a major problem, sufficient explosion-proof functionality can be achieved. FIG. 4 shows a sealing body 4 constituting a part of the exterior case 2 shown in FIG. This gas exhaust window 40 is closed with a gas permeable plate 42 made of the aluminum-tin alloy material. FIG. 5 shows the embedded state. With this configuration, although it is not expected to improve the acoustic characteristics of the previous embodiment, a sufficient selective gas evacuation effect can be obtained. Further, FIG. 6 shows a case in which a gas exhaust window 40 is formed in the sealing body 16 of the exterior case 22 shown in FIG.
The gas permeable plate 42 is similarly embedded inside it. According to such a configuration, evaporation of the electrolytic solution can be suppressed and only hydrogen gas can be discharged from the exterior case 22. Next, experimental results of this invention will be explained. The electrolytic capacitor used for the experiment was of the type shown in Figure 1, with a capacitance of 14000 μF and a diameter of 35 mm.
mm x length 50 mm, and the outer case was made of aluminum (0% tin) and aluminum-tin alloy containing 5% and 10% tin. tin 5
% and 10% are weight ratios to aluminum. The test method is a load test at 85℃, and the measurement items are leakage current LC (μA), change in capacitance C (%), tangent of loss angle tanδ, and change in weight W △W
(%) The measurement results are shown in the table below.

[Table] Figure 7 shows the time-leakage current characteristics, Figure 8 shows the time-capacitance change rate, Figure 9 shows the time-loss angle tangent characteristic, and Figure 10 shows the time-weight change rate. , In each figure, A is a case with 0% tin, that is, with an external case made of pure aluminum, and B is a case with 5% tin.
C is 10% tin. Combining these experimental results, the leakage current LC
(μA), capacitance C (μF) and tangent of loss angle
Although no major change is observed in tan δ, the weight change ΔW (%) shows that as the tin content increases, the weight decreases almost in proportion.
Although this weight reduction means that the electrolyte in the outer case evaporates, it can be inferred that the hydrogen gas in the outer case is efficiently discharged compared to the amount of evaporation. In particular, this experimental result was measured at a high temperature of 85°C, and evaporation from the sealing body is also considered, so if the sealing is made strong, good hydrogen gas permselectivity can be achieved at room temperature. It is something that can be done. Moreover, since the hydrogen gas permeability is proportional to the tin content, it is possible to create an exterior case with a tin content that matches the size of the electrolytic capacitor, the operating temperature, and other conditions. Also, according to listening experiments of this type of electrolytic capacitor, it was found that the characteristics of the reproduced sound change depending on the tin content. , an electrolytic capacitor having desired acoustic characteristics can be obtained, and the acoustic characteristics can be improved. As explained above, according to the present invention, since an alloy material of aluminum and tin, which is mainly made of aluminum, is used for the exterior case, it is possible to obtain acoustic characteristics that cannot be obtained with aluminum alone. Since the case is porous, hydrogen gas selective permeability can be obtained, and hydrogen gas can be efficiently discharged.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of an electrolytic capacitor showing a specific embodiment of the exterior case for electrolytic capacitors of the present invention, Fig. 2 is a longitudinal cross-sectional view of an electrolytic capacitor showing another embodiment, and Fig. 3 is a longitudinal cross-sectional view of an electrolytic capacitor showing a specific embodiment of the electrolytic capacitor exterior case of the present invention. A partially cutaway side view, Fig. 4 is a plan view of the sealing body, Figs. 5 and 6 are longitudinal sectional views of the sealing part showing the gas discharge structure in the sealing body, and Fig. 7 shows the time-leakage current characteristics. Figure 8 is an explanatory diagram showing the time-capacitance change rate, Figure 9 is an explanatory diagram showing the time-loss angle tangent characteristic, and Figure 10 is an explanatory diagram showing the time-weight change rate. be. 2, 22, 36... Exterior case, 4, 16...
Sealing body, 10, 32... Electrolytic capacitor element, 4
0...Gas exhaust window, 42...Gas permeation plate.

Claims (1)

[Scope of Claims] 1. In an exterior case for an electrolytic capacitor in which an electrolytic capacitor element is enclosed, the case is constructed by molding a porous alloy material plate mainly composed of aluminum and tin; An exterior case for an electrolytic capacitor, characterized in that the content of is set within a range that does not cause the alloy material plate to lose its plasticity to the extent that it can be molded. 2. A patent claim characterized in that a gas exhaust window is formed in a sealing body constituting a part of an exterior case, and a gas permeable plate made of the aluminum and tin alloy material plate is provided on the gas exhaust window. An exterior case for an electrolytic capacitor according to item 1.