DE1764546B1 - REGENERATIVE ELECTRIC CAPACITOR - Google Patents

Description

The present invention relates to a reaenerierfähi-en electrical capacitor, opposite polarity in the e C coverings offset from one another on the two sides of dielectric films metallized are, in which said dielectric films are one above the other anaeordnet that are opposed to homopolar coverings, and in which the coverings over end-face contact layers are connected to power supplies.

It is known that regenerating capacitors can be wound, folded or stacked from metallized plastic films, in such a way that opposing poles are led out to different sides of the roll or stack and that these linings are each carried out on one side by the application of an electrically conductive layer, are preferably connected to one another in an electrically conductive manner by spraying on a metal layer. In this case, by means of a suitable lateral offset of the foils of equal or unequal width, depending on the structure, it is ensured that the coverings are made accessible on the respective desired side of the end contact.

What these arrangements have in common is that the insulating film and air gap are always connected in series as an effective dielectric. Although this air gap can be kept small - for example by high film pulls and / or tempering - it can generally not be completely eliminated as a result of the production-related surface roughness and thickness fluctuations of the insulating films. In many cases, z. B. with flat windings, there is also the risk that air gaps will re-form in the condenser over time as a result of temperature influences or other aging processes.

Uni to eliminate the air gap with its disadvantages, it is known from German patent specification 426 879 and German patent application P 23211 VIII c / 21 g , issued on December 28, 1950 , to entangle dielectric strips metallized on both sides to form electrical capacitors. With these capacitors, the temperature coefficient of the capacitance and the constancy of the capacitance only depend on the dielectric constant, the film thickness, the elastic modulus of the film and the winding pressure. These are parameters that change with temperature in a strictly reproducible manner.

Nevertheless, these capacitors have various disadvantages which have an unfavorable effect on the operation of the capacitor. First and foremost, the problematic »indirect # contacting of one covering over the other covering, as used in the subject matter of German patent application P 23211, should be mentioned here. Although the deposits are in close contact, they are each covered with an oxide layer so that the current has to cross these two oxide layers. In an idealized way, this double oxide skin can be ascribed a resistance and a capacitance per unit area, the product of which gives a time constant. If alternating voltages (including voltage pulses as a result of switching operations) are fed to the directly contacted areas with such high frequencies that their period durations are of the same order of magnitude or less than the time constant of the oxide layer, then a voltage develops on both sides of the oxide layer that leads to breakdowns and thus leads to a reduction in capacity and interruption of the relevant indirect contact as soon as it has reached the order of magnitude * - of 1 to 5 V. Even if cliling has not yet occurred, an increase in the loss factor and a decrease in the effective capacity must be expected with increasing frequency. A particular problem here is that the time constant of the oxide skin can still change continuously due to temperature changes, storage, electrostatic and mechanical forces, etc. The use of covering metals whose oxide layers are very thin or relatively poorly insulating (e.g. tin) is ruled out, as these metals impair the regeneration process.

Another disadvantage of the known capacitors is that in the event of a breakdown through the insulating film on both sides of the penetration channel there is a double layer of pavement, which jeopardizes good regeneration will.

The object of the invention is to provide a regenerating capacitor with to build a high constant capacity and perfect contacting.

This problem is solved according to the invention, while avoiding the disadvantages listed above, in that a film is inserted between two equipolar coverings, which extend completely or almost to the front edges of adjacent dielectric films, so that the covering edges are rough up to the front edges Raising beyond the foil and that the stirrer contact layers grasp the edges of the covering protruding beyond the foil.

The individual foils can be made of an insulating material or a metal exist.

From the German patent 426 879 it is known in an electrical capacitor to stack metallic dielectric strips on both sides and to insert insulating layers between mutually facing and conductively connected metal coatings of the same potential. However, this patent does not show a technically feasible way how a suitable electrical contact can be established between the same poles and the external power supply. because the covering layers do not extend to the front sides and are covered by insulating layers.

The task of providing a safe, i.e. H. Establishing direct contact with the respective face-side contact metal layer (Schoopschicht) for each coating is only achieved by the measures of the invention, namely by the fact that - as described above - the coatings to be contacted are each on each face from from which they are to be contacted, preferably up to the edge of the foils on them, but at least up to the edge of the foil in the field-free space, so that each coating is injected through the gap created between the non-polar coatings or in some other way contact is made directly, i.e. without intervening oxide layers.

With reference to the figures, the invention is intended to be more detailed on the basis of exemplary embodiments explained.

The F i -. 1 and 2 show sections through stacked capacitors, which z. B. are produced according to the drum winding process. The capacitor strips are wound up on a drum and the ends are provided with contact metal layers. The so hearted mother's wrap. is then in the desired partial capacities z. B. sawn. The dielectric foils 1 wear on both sides each opposing pole coverings 2, which z. B. can be vapor-deposited aluminum layers. The interposed foils 3 and their air gaps on both sides are in the field-C-free space and do not contribute to the capacitance. This structure makes it electrically conductive in a known manner, for example by spraying on a metal layer with the equal poliaen coverings .! connect It allowed himself to zen only simple Bela ze ueiienüber so that a sieheres rc, - # is izewahileistet enerieren in addition, the re-enerierverhalten be further improved by appropriate selection of the insulating material for the films 3 in a known manner..

The dead volume occupied by the “field-free” foils 3 in the F i 1 can be achieved by a structure according to F i e. 2 can be reduced by half. The one-ele # ti foil 3 extends approximately to the center of the capacitor body and is located between "leichgepolten surfaces in the capacitor body half in which the end contact layers the corresponding _eleichgepolten, to zr egenüberliegenden, -. - separated by the inserted sheet coverings The single film does not extend to the outermost edge of the metallized dielectric films 1, but leaves the protruding edges of the vapor-deposited layers free for reliable contact the same as f or F i g. 1. Notwithstanding the F i g. 1 liezen partially again two Bela-e each other. the re-enerierverhalten is not impaired. because the respective Gegenbcläge in this case C4 CZC always easy A further advantage of the arrangement according to F i 2.2 is that even when the sheets 2 do not stick to the dielect Rikumsfolien 1 the field-free foils 3 as well as their bilateral air gaps remain field-free. Only the air gap between the foils 1 is included in the field in accordance with the deck unasfeliler of Bc] ä2e. The individual insulating films 3 can be used to improve the regeneration properties.

In those cases of application in which the dielectric strength of the dielectric is hardly used, a structure according to FIG. 2 can be advantageous, in which the intermediate foils 3 are not made of insulating material but of metal. By choosing the type of metal and the thickness ratios, the temperature coefficient of the capacitance can be influenced and the heat dissipation of the coil can be improved.

Claims (2)

Claims: 1. Regenerative electrical capacitor, in which opposing polarity layers are offset from one another on the two sides of dielectric foils are metallized, in which these dielectric foils are arranged one above the other in such a way that homopolar linings are opposite one another, and in which the linings are connected to power supplies via end contact layers, characterized in that between each two entirely or almost up to the end-side edges of adjacent dielectric films (1) reaching, homopolar coverings (2) a film (3) is inserted so that up to the end edges projecting covering edges on the film (3 ) protrude and that the front contact layers capture the covering edges protruding beyond the film (3). 2. Regenerative electrical capacitor according to claim 1, characterized in that the inserted film extends in the direction of the Belaasränder trailing behind the film edges at most up to the center of the capacitor body. 3. Regenerable electrical capacitor according to claim 2, characterized in that the inserted film consists of metal. 4. Regenerable electrical capacitor according to claim 1 or 2, characterized in that the inserted film consists of an insulating material.