JP2008251837A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having a characteristic superior in vibration resistance. <P>SOLUTION: The electrolytic capacitor is provided with a capacitor element 1 where a separator is arranged between anode foil and cathode foil and they are wound, a bottomed case storing the capacitor element by impregnating electrolyte in the element and a sealing member 4 sealing an opening side of the bottomed case 3. A heat shrinkable tape layer 2 is formed in an outer periphery of the capacitor element. A width size of a tape is contracted by heat-shrinking a heat shrinkable tape layer, and the tape is curve and/or bend-deformed in a radial direction so as to fill a clearance between the bottomed case and the capacitor element. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a capacitor having excellent vibration resistance.

  As is well known, an electrolytic capacitor is made of an electrode foil that serves as an anode and an electrode foil that serves as a cathode, with a separator interposed therebetween, and is wound into a laminated form, and the end of winding is thermoplastic, such as highly heat-resistant polyphenylene sulfide. The capacitor element is secured by an element retaining tape, a bottomed case that is stored in a state in which the capacitor element is impregnated with an electrolytic solution, and a sealing member that seals the opening side of the bottomed case.

The dimension in the radial direction of the capacitor element is adjusted by the length, thickness, etc. of the electrode foil and the separator constituting the capacitor element so as to obtain a necessary capacitance.

However, the electrolytic capacitor is designed such that the outer diameter of the capacitor element is smaller than the inner diameter of the bottomed case so that it can be easily inserted into the bottomed case. A gap was formed between the outer diameter of the element and the inner diameter of the bottomed case (see, for example, Patent Documents 1 and 2).

JP 7-226346 A JP-A-8-55762

When the electrolytic capacitor is used in a vehicle, for example, when applied to an electronic device for engine control, the electronic device may be mounted in the vicinity of the engine or directly in the engine, and may be subjected to large vibrations.
From such electronic devices, electrolytic capacitors having excellent vibration resistance are required.

However, the conventional electrolytic capacitor has a lead wire drawn out from the electrode foil and a tab portion that connects the electrode foil and the lead wire due to the vigorous oscillation of the internal capacitor element under vibration conditions premised on engine mounting. There is a problem of disconnection.

The tab portion connecting the electrode foil and the lead wire is firmly fixed by a sealing member, and a portion processed into a plate shape so as to be easily connected to the electrode foil is connected to the electrode foil. Is fixed to an external member only by the lead tab portion.

When the product is placed under severe vibration conditions in this state, the gap between the inner diameter of the capacitor element and the bottomed case is large, and the capacitor element vibrates with the portion where the lead tab of the capacitor element is fixed to the sealing member as a fulcrum. Each cycle oscillates greatly in the vibration direction, the lead tab portion receives a strong force in the vibration direction and the expansion and contraction direction, the stress concentrates on the weakest portion of the lead tab portion, and the lead tab portion is disconnected.

The present invention solves the above-described problem, and includes a capacitor element formed by interposing a separator between an anode foil and a cathode foil, and storing the capacitor element in an impregnated state with an electrolytic solution. In an electrolytic capacitor comprising a bottomed case and a sealing member that seals the opening side of the bottomed case, a heat-shrinkable tape layer is provided on the outer periphery of the capacitor element, and the heat-shrinkable tape layer is thermally shrunk. Thus, the width dimension of the tape is reduced, and the tape is bent and / or bent in the radial direction to fill a gap between the bottomed case and the capacitor element.
In addition, as an example of the shape (cross-sectional shape) of the above bending and / or bending deformation, any one of end face curl shape, bellows shape, drum shape, drum shape, mountain shape, or a combination of two or more of these The thing which was done is mentioned.

The electrolytic capacitor according to the present invention is excellent in vibration resistance. For example, it has improved vibration resistance when mounted in the vicinity of an automobile engine or directly on the engine.

Filling the gap between the capacitor element and the inner diameter of the bottomed case reduces the space in which the capacitor element can move in the bottomed case in a vibration environment, suppresses the swing of the capacitor element, and causes lead wire breakage. By reducing the stress applied to the vibration direction of the lead tab portion or the expansion and contraction direction, disconnection of the lead tab portion is suppressed.

An embodiment of the electrolytic capacitor according to the present invention is shown in FIG.
In FIG. 1, a capacitor element 1 has a structure in which an insulating separator is interposed between an anode foil and a cathode foil, and this is wound, and the end of the winding is applied to a high heat resistant element stop tape. Further, a heat-shrinkable tape layer 2 is provided on the outer periphery thereof.
The heat-shrinkable tape layer 2 is sealed by the bottomed case 3 and the sealing member 4 in a state in which the outer periphery of the capacitor element 1 is circulated more than one and a half times.

In order to make the heat-shrinkable tape layer 2 constant, it is preferable to use a constant width regardless of the size of the capacitor element 1.

When heat is applied to the heat-shrinkable tape, the tape shrinks in the width direction while being bent, and fills the gap between the outer diameter of the capacitor element 1 and the inner diameter of the bottomed case 3. Can be prevented from swinging.

Depending on the height of the capacitor element, the tape position and the number of windings are changed to prevent the capacitor element from swinging due to vibration.

Next, an electrolytic capacitor having a rating of 25 V, 2200 μF (size: φ16 × 31.5 mmL) was used as a sample, and a capacitor in which the difference between the diameter of the capacitor element 1 and the inner diameter of the bottomed case was 0.3 mm was prepared.

As an embodiment of the present invention, a polyethylene tape having a thickness of 0.1 mm is wound as a heat-shrinkable tape on the outermost periphery of the capacitor element, and the tape is stored in a bottomed case and sealed with a sealing body, and then in an atmosphere at 150 ° For 180 seconds, the tape was shrunk to prepare a capacitor element and a bottomed case in close contact with each other. At this time, it was confirmed that the deformation shape (cross-sectional shape) of the tape was a combination of a mountain shape and an end face curl shape.

As a conventional example, a capacitor element in which a polyethylene tape is not wound around the outermost periphery was prepared.

These were subjected to a vibration test with the number of samples n = 50 after fixing the entire product (thickness of electrolytic paper: 50 μm). After the vibration test, the electrical characteristics of the capacitor were investigated and the presence or absence of disconnection was determined. The results (number of rejected products / number of test products) are shown in Table 1.
The vibration test conditions were as follows.
Sinusoidal vibration: f = 10 to 2000 Hz, maximum amplitude: 1.5 mm, maximum acceleration: 30 G,
Sweep speed: 1.0 oct / min (logarithmic sweep), vibration direction: X, Y, Z, 3 axes, 4 hours each

From Table 1, all the products according to the examples in which the polyethylene tape was wound and heat-shrinked were not abnormal, whereas the products in the conventional example in which the polyethylene tape was not wound and heat-shrinked were all disconnected in the lead tabs. It can be seen that the vibration of the capacitor element is suppressed by the present invention.
In the above embodiment, it was confirmed that the shape of the tape bending and / or bending deformation (cross-sectional shape) was a combination of a mountain shape and an end face curl shape. Even if it is any one of the shape, bellows shape, drum shape, drum shape, mountain shape, or a combination of two or more thereof, the same effect as described above can be obtained, and the shape is limited. It is not a thing.

It is a schematic longitudinal cross-sectional view of the aluminum electrolytic capacitor which shows the Example of this invention.

Explanation of symbols

1 Capacitor element 2 Heat-shrinkable tape layer 3 Bottomed case 4 Sealing member 5 Lead wire

Claims (1)

A capacitor element formed by interposing a separator between an anode foil and a cathode foil and wound, a bottomed case for storing the capacitor element in an impregnated state with an electrolyte, and an opening side of the bottomed case In an electrolytic capacitor comprising a sealing member to be sealed,
The bottomed case is provided with a heat-shrinkable tape layer on the outer periphery of the capacitor element, the heat-shrinkable tape layer is heat-shrinked to reduce the width of the tape, and bend and / or bend in the radial direction. An electrolytic capacitor characterized in that a gap between the capacitor element and the capacitor element is made up.

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