US1870961A - Condenser - Google Patents

Description

Aug 9, 1932 A. NYMAN ET AL. 1,870,961

coNDENsER Filed Aug. 4, 1927 3 sheets-Sheet 1 30 Z9 Z6 9 6 6 Z7 WLM m cl ATTORNEY Aug. 9, 1932. A. NYMAN ET A| CONDENSER I5 Sheets-Sheet 2 Filed Aug. 4, 1927 ug- 9, 1932- A. NYMAN ET AL CONDENSER 5 Sheets-Sheet 5 Filed Aug. 4. 1927 ddl 4 4 4 4- nl 4 4 4 4 5 |.I "lo 1l..

Patented Aug. 9v, 149/32 UNITED STA 'ras PA'raN'roFl-"lca ALEXANDER NYMAN, OF DOBBS EERRY,AND WILLIAM vIDU'IBIIIILIER, E'W ROCHELLE NEW YORK, ASSIGNORS TO DUBILIER CONDENSER CORPORATION, OF NEW YORK,

N. Y., CORPORATION OF DELAWARE CONDENSEB appueaaon mea agua 4, 1927. semi mi. monza This invention relates .to electrical condensers, and particularly condensers designed primarily for use in communication by radio.

The structure of the condenser comprises 'a plurality of stacks or sections of alternating layers of conducting material and d1electr1c, e

arranged radially with respect to a common center or axis, and maintained in position under a required degree of compression.

This particular condenser is intended for use with short electric waves or oscillations, which cause the terminals to have relatively great tendency to heat. An object of the invention is to overcome this tendency by making almost the entire casing of the condenser consist of terminals, the base or body of the casing serving as one terminal and the cover or lid of the casing serving as the other.

A further object is to arrange certain external surfaces, as will be made clear in the description, to provide a surface ath .such as currents of this nature will pre erably take. A further object is to provide eilicient insulation between the two large terminals by having part of the casing made of insulating material between the loase` andcover.

Anumioer of other objects of the invention are secured by imparting a concavo-convex configuration to the exterior of the casing, adapted to permit the condensers to be nested or piled up in stacks when suchva combination is desired and yet leave suflicient space inside -for insulating purposes. The conguration in question is vconducive to ease of assembling and mounting the condenser in its ultimate operative location, and still further increases the ease with which the condenser radiates heat, even when not provided with all the features specifically mentioned herein. Also the necessity for long conductiing strips to connect the interior sections with the exterior terminals is obviated by this concavo-'convex configuration.

A still further object is to provide a. strong compression ringLwitliin which the stacks can be placed `to form a sub-assembly unit prior to final assembly-'within the casing.

i'lhe drawings illustrate a preferred form of the invention; in which: i

Figure l is a horizontal view of a condenser Yaccording to our invention partly in plan and partly in section on the dotted line 1-1 of Figure 2; Y

Figure 2 is a vertical cross section taken longitudinally of twoopposed condenser sections or stacks; y

Figure 3 is an exterior view, 1aoeing a side elevation and on a somewhat smaller scale than Figure 2;

Figure 4 is a plan view of a contact plate for the condenser;

Figure 5 is a side elevation of said contact plate in finished form;

Figure 6 is a diagrammatic view showing the path of current through several of the condensers. when nested, the condensers loeing taken in section along line 6 6 of Figure l;

Figure 7 is a cross section in the same vertical plane as Fi ure 2 hut shows one'of the conductors modi 'ed; ,i

igure 8 shows part or Figure 7 enlarged; an

Figure 9 is a diagrammatic view showin the path of the current through the modified arrangement of Figure 7;

ln the drawings the same numerals identify the same elements throughout.

A small boxlike metallic shell 1 constitutes half, more or less, of the outside casing. A plate 2, dish-shaped or concave, forms the lid or cover of the casing. Between the shell and cover a wide ring or short cylinder 3 of insulating material, such as glass, forms the greater part of the sides of thecasing and thoroughly insulates the -lid 2 from the shell or body 1. The casing surroundsand supl daft-sided block 8 lloy outside pressure plates 9. Fach stack or body 7 comprises a numrise to losses.

ber of units 11, each composed as` usual ofp alternate la ers of electrically conductive elements suc as metal foil and of insulation such as mica. These units are spacedapart by separator blocks consistin of a core y of'insul'ating material surrounde by a sheet of metallic conducting material. 'In the modification' illustrate the units 11 are shown relatively thin and the separator 4blocks 10 relatively thick. 'The cover `2 of the casin is held in place by means of screws 12 threa ed into holes tapped -into the central block 8. An opening extending entirely through the condenser permits access of the.

outside air to the interior' of this hollow block and introduces acooling action 'at'the center of the condenser where it is most needed.

Flange 57 at the interior end of thehollow block 8, and flange 58 at the center of the casing 1 .serve to support a tube of insulation 56. Tube 56 is'held in lplace by means of thread ring 61 engaging t reads -in casing 1. Gras` kets 59 and 60 are located at the ends of the insulating tube. Holes 62 are provided in ring 61 for the application of a Spanner For assembling thel four stacks in place, insulating blocks 14 are inserted to prevent access of current to the large mass of metal in the block 8, `where it'would setup eddy currents and produceheating. No attempt' is made to insulate the block 8 from the terminal Ior cover 2, for mere voltage or electric is placed between the part 3 and the cover,

and is shielded by the flange 18.

The flexible metal conducting plates 20, shown in Figures 1 and 6,'connect the outer` ends of each stack to themain part ot the casing 1. This casing 1 has a rimlor outer ange 21 which surrounds a strong compression ring 22, andupon assemblage thisring 22 is fast to the casing 1 by means of screws 23. The ring 22 rests on a shoulder 24 within the rim'21. v

Other insulating blocks 25 are dsposed at the outer ends of the-stacks. These blocks 25 serve a purpose similar to that of. the blocks 14, as they prevent a How of current through the heavy masses of metal in the thrust blocks 9, with the consequent eddy currents and heating effects. No attempt is made to insulate thrust blocks from the voltage on the terminal or sheet 1.

Heavy pressure is exerted upon each ot the stacks by large screws 26 which'pass through the ring 22 but are not threaded into the ring 22, beingthreaded instead into thrust blocks 27. These blocks distribute the stress a con-l siderable way around the ring 22 and keep it from being localized at one point, which wouldv be right at a place of special weakness;

namely, where ythe hole is drilled to allow' would not pinch so as to prevent rotation of'.

the screws. The outer ends of these screws are provided with the usual slots 29. The holes 30 in the ring 22, through which the screws 26 ass, are large enough to permit considerab e relative movement of the thrust blocks 27. p v

Figure 1 of the drawings shows the ring 22 thickened out or strengthenedmidway of the thrust screws. This feature isnot always essential. The ring is usuallynmade of uniform thickness throughout and the resultant springiness is somewhat desirable as it keeps a continuous pressure on the stacks under. varying temperatures. However, if in making somev particular size or proportion of this condenser, such a uniform section ofthe rfng proves unduly weak, then reinforcing or thickening midway of the thrust screws can be adopted. The ring is' made of a nonferrous metal, such as phosphor bronze, to avoid additional eddy currents that would creep in if a magnetic material were located so nearthe oscillating currents as this ring 22.

Having the ring 22 separate vfrom the shell 1 permits the casing to be made of reasonably thin material. This could be accomplished by imbeddng the heavy ring in a cast casing but such a method would not per' mitv ease of assembling. After the subassembly within the ring is complete, the ring 22 is then fast to the body of the casing 1 by means of screws 23, thus making-the ring rigid with the casing; and producesall the advantages that could be secured by embedding the ring into the shell 1 by casting the shell about the ring.

The casing may be filled with Wax or other insulating material, poured into the casing lil in liquid form and allowed to harden and v embed the sectons 7 and other parts. A

A gasket 31 of soft material, such as rubber, isintroduced'betwveen theglass ring 3 and the ring 22. This bulges out sideways and prevents leakage of wax past the flange 21, as well as between the rings 3 and 22. The aperture closed by plug 32 permits filling with wax andthe exit 'of air bubbles when the condenser is inverted with respect to the i flanges of plate 16. This subassembly is n el) placed within the casing 1 and fastened by means of screws 23 on the shoulder 24. Gasket 31, insulating ring 3 and gasket 19 are then laid on, whereupon the cover or lid 2 is put on and fastened by means of screws 1:2.-

The compression of the gaskets 3 1 and 19 by means of screws 12 does not disturb or upset the stacks 7 because they are under relativelyy great pressure from the ring 22. Tube 56and ring 61 are then assembled.

In order to permit nesting of a plurality' of these' condensers, the inside curve of the hollowed-out cover 2 is made on a contour' of greater diameter than the outside curve of the convex bottom of the shell 1. This is to make sure that no ball-and-socket action takes place when a number of these condensers are stacked up. Moreover there are slight elevations 35, shown in Figure 3, on the shoulder 34 of the shell 1. The peripheral flat part of the top of the lid 2 will contact firmly with these elevationsv on the bottom of the casing of the adjacent condenser and allow circula-v tion of air between consecutive units of these condensers when they are nested. This circulation conducts heat away from the terminals, otherwise some of the purpose of the hollow block 8 would be defeated.

The general form of the condenser is not made concave-'convex merelg' to permit stack! ing or piling of a series of t ese units, for obviously they could be stacked up justas well if they were disc-shaped. Having decided to make the terminals as large as-possible, owing to their tendenc to heat and having used the entire top an entire bottom ofthe condenser as the two terminals, we still have theproblem of getting the current from these outside terminals to the ends of the sections 7 without long connections; for these connections would heat up. The best expedient is tov bring down one of the terminals at the center to contact with the inner ends of the stacks and to shape the periphery of the shell or body 1 so that it practically touches the outer ends of the stacks. Obviously the center of the bottom will have to bulge away from the inner ends of the stacks, they being of opposite potential with respect to the bottom. Since the periphery of the shell 1 is brought clear into the equatoror centraltransverse plane of the condenser taken as 'a whole, the periphery 'of the top must'be spaced from the outer ends of the stacks, to provide room for further need is to make the inside curvature of the hollow top greater than the outside curvature 'of the bulged bottom, sol thatthe condensers still can be stacked.` Sincethe bulge of each successive unit is largely within the hollow ofthe preceding unit, the over-allv length of a plurality of the condenser units is much smaller than if the casings were relatively iat' or shallow.

Of course the layer-s of metal foil and mica in the units 11 can be arranged in any manner, and the units 11 grouped and connected as required.

1 Currents of very high frequency, such as the ones that the herein described-condenser is adaptedto receive, have certain attributes and conform to definite laws; and these laws are quite at variance with those which applyto low frequency alternating currents.

First: They follow the outside of a conductor. Second: They do not penetrate even a slight depth of solid metal if any outside path even of considerable length offers itself. Third: They do not follow into refentrant angles in the surface of a conductor, such as those that frequently occur at joints.A

The -following by such current of the outside of a conductor does not take place in such a simple manner as would be expected at first sight, for the current may not distribosi ute itself all over the/superficial area of the conductor. Assume that the current were passed longitudinallythrou h a metal bird cage or through a cylinder o netting, such as is placed around small trees, the current would not distribute itself" completely around the surface of each individual wire,

- but would travel along onelside only of each wire and that side would be the outermost one. with respect to the longitudinal axis of the cage or cylinder of netting. Assume again that such a current were being passed longitudinallyl through a sheetinetal cone, say from the edges of the base tothe apex j (the cone, of course, having two surfaces, one in side and one outside with respect'to the longitudinal axis), lthe current would not split, half of it travelling along each surface, but all of the current would follow along theutside surface, While none of it would utilize the inside surface. With respect to solid metal, the currentv does not even penetrate a very thin -pieceof sheet metal if a surface path that is not of extreme length and complication offers itself. Furthermore, the width of the'f'surfac'e path is of some importance, for an apparently crooked or curved lp ath may -o'er scarcely any resistance if the path is quite wide, s'o as not to require any great surface' density per unit of area.l

The aversion of these currents to flow into re-en'trant angles, such as those found adja- 55 insulation between it and the body `1. 1F lustrated by Litz wire, for the current 'instead ofl following any'. 'v'en surface after the wire passes into the ody of the platted mass of wires, simply leaps across the intervening space andtakes up itspath along 5 the surface of some other wire which' happens to be at the surface of the platted mass. Such currents heat up such wire excessively. Assume that the path of a high frequency current is at right angles to the contact jointl between two conductors, the joint being so shaped as to make a deep recess, depression or crotch' where the two bodies join, then the current instead of following all the way into the bottom of the recess 'and coming up at the opposite side, usually leaps from edge to edge so to speak, penetrating the intervening atmosphere; and this results in considerable heating effect. current has a tendency to follow along a tangent to the general surface rather than to ollow in detail into re-entrant angles and depressed irregularities.

Assume that such a current were being transmitted along a com licated mass of conducting wire cable or a aze of wire platted Litz fashion, the mass of wires, however, having a definite boundary and a fairly uniform cross section, such as circular, then it would be found that all of the interior portions of the wires are quite useless as conductors, for even if from time to time a given interior wire came to the surface the current would all be localized along the exterior of the cylindrical massl following any portion of a wire that was exterior with respect to the central axis and jumping from that portion to some other wire that had a part on the exterior at any point where the first mentioned wire passed to the interior. We have 40 taken account of these principles for our invention.

In the development4 of this invention provisionfor the path of the current was not limited tof merely enlarging the terminals l for the same. The certainty with which high frequency currents seek the outside of any conductor was recognized. Referring to the diagram, Figure 6, attention is called to the median line 40-41. The current in travelling along various paths t-o get through one 'or several condensers progresses in a general direction parallel to the line 40-41 and in traversing a mass of metal such as the top 2 it will follow alon the surface 42 rather than the surface 43 cause 42 is outside with respect'to the line 40-41. Top 2 has two surfaces 42 and 43 and since it is a fact that these high frequency currents travel on the surface of a mass of metal instead of through the interior of the same, it follows that the path will be either 42 or 43. But, looking at Figures 1 and 2,4it willbe seen. that the cross section of the general path of the current' into the condenser by means c5 of terminal 2 iscoincident with the crosssectional area of the entire condenser. Look- In other words, theA jacent theinnermost element of each stack 7 ;l

through the stacks 7 (so to speak) as indicated by arrows 44 tothe conducting plates 20 and the current follows the plates 2O till solid metal is reached where 20 is clamped between ring 22 and bottom 1. That is, in between the parts 22 and 1 conductor. 20 has neither surface free. But referring to the plan, Figure 1, it will be seen that the plates or 'stri-ps 20 occupy a small part only of the periphery of the shoulder 24 of the base 1. At all other points on this shoulder there is an open space between shoulder 24 and ring 22, as seen in the right hand half of Figure 6, equal to the thickness of the strips or plates 20.l In these open spaces the current travels across the surface of the shoulder as indicated by the line 45. Upon reaching the rim or flange 21 it passes up the inner surface 46 of .the same and then down the outer surface 47 of the fiange 2-1 to the surface 48 of the flange 18 of the lnext adjacent condenser, thence-to surface 42'of the next vcondenser and so on. The surfaces traversed bythe current are all indicated in heavy black lines.

Here. several questions are pertinent.. Why

does not the current pass directly through the casin 1 when it reaches that part of the strip 20 t lat is clamped between ring 22 and casing 1? And when it reach's Han e 21 why does it not pass directly through t e ange.

In both instances the reason is that a long sur.l

face path is preferable to or offers less resistance than a much shorter path through solid metal.y Why is not the strip 20 always turned the other way so as to contact with the upper edge of flange 21, as illustrated in Figures 7, 8 and 9? Because of Various structural diculties such as interference with the ti htness of gasket 31. Also, because a s ort crooked path of large width or area such as the 46-47 path offers relatively little additional resistance provided the current does not have to cross through a thickness of metal. v

Reviewing the entire path of the current as shown by the heavy lines of Figure 6 it is seen that at no point is the current forced to cross or penetrate any thickness of metal, not even the thin strips 15 or 20. j j

Referring more particularly to Figures 7,

8 and 9 it will be noted thatstrip 20 is replaced by a strip 51 which passes above the ring 22instead of below and passes beneath the rubberv gasket 31. It is fast to the upstanding rim 2l by means ofa thin strip of metal 52 held byv means of screws 53.

does notv flow through the sections 7 of the condenser, but flows lonly through the metal parts united to the terminals of the condenser sections 7.

The invention is not limited to the modifi-- cations described above for illustrative pur-- poses but numerous lchanges can be made without exceeding the scope of the following claims.

Having described my invention, what I believe to be new and desire to secure and protect by Letters Patent of :the United States I. A condenser comprising a plurality of radially arranged sections and a casing with portions of its area adapted to serve as terminals, one part of the casing being shaped to make direct contact with the common center of the sections, and another part thereof shaped to make contact with the outer ends of the sections.v v

2. A condenser comprisin a plurality of groups of dielectric and con uctive elements, and an enclosing casing having large portions of its surface forming two conducting areas,

one of'said areas curved inward to make di.

rect contact with one end of each group and the other of saidareas curved to make direct contact with the opposite end of each group. v

3. A condenser comprising a casing having 'a flat side with a centrally located convex area, and a flat side opposite to the rst mentioned side having a concave area of such relative contour that a duplicate condenser can rest with its convex area Within said concave area with the flat side of the duplicate lcon.- denser contacting with a fiat side of the first mentioned condenser.

4. A condenser casing' as stated in claim 3 in which one of the flat sides is provided with slight elevations to provide a passage for the circulation of a cooling medium between the first mentioned condenser and the duplicate condenser.

5. A condenser comprising a casing, a central block therein and vsections of condenser elements abutting the central block, said block being hollow and open to the exterior of said casing.

6. A condenserV comprising a casing, a central block therein and sections of condenser elements engaging the central block, the casing being curved inward to serve as a terminal for said stacks, and comprising a means for ventilation of the central-block'.

7 A condenser including a body, a surrounding frame to compress the body and a casing to enclose the body, the casin being 4separable from the frame for assemb y pur-- poses and fastened 'firmly to the frame while the condenser is in use.

8. .In a condenser the combination of a central abutment, a plurality of sections of dielectric and conductive velements arranged radially of the abutment, insulating blocks between the sections and the central abutment,

a conducting plate between each section and its respective insulating block, a terminal plate on top of the abutment adapted to contact with all the conducting plates.

9. A condenser comprislng radially arranged sections, a central hollow block at the inner ends of said sections, a concave ter-A minalcontacting at its center withthe inner ends of said sections, a. convex terminal contacting at its periphery with the outer ends of said sections, an insulating ring extendin from the periphery of the concave termina to the outer ends of said section, and a cylinder of insulation extending from the center of the convex terminal tothe inner ends of the sections, said hollow block, concave terminal, convex terminal, insulating ring and insulating condenser.

10. A condenser comprising condenser sections arranged radially aroundv a hollow cylinder completely enclosing said block, a casing arranged for stacking a plurality of such condensers, a passage through the hollow block to register in consecutive condensers of a stack, forming a continuous passageway.

ll. A plurality of condensers in containers, a passage through the body of each of said containers, means for stacking said containers to register said passages with each other, so that a continuous passageway is formed.

12. YA condenser adapted for use in radio frequency circuits, comprising a casing member surrounding a plurality of radially disposed stack sections, metal end closures for the casing member, each closure member forming one terminal of the condenser'and having a relativel large surface, one of said closure members eing connected to each of the inner ends of the stack sections, and the other end member being connected to each of the outer ends of the stack sections, whereby high frequency currents will pass with-out heating the condenser or terminals. 1 13.' A high frequency condenser having an insulating casing member surrounding a plurality of radially disposed stack sections, mt-

`los

being connected at its peripheral portions to each of the outer ends of the stack sections, .whereby high frequency currents will pass without causing heating of the condenser or terminals. y

14. A high frequency condenser having a. tubular caslng member of insulating material enclosing a plurality of radially disposed stack sections, metal end plates' for the cas- 5 ing member, each plate forming one terminal of the condenser and having a relatively large surface, one of said end plates being connecte at its central portion with each of the inner ends of the stack sections, the other end 10 plate being connected at its peripheral portions to each of the outer ends of the stack sections, whereby radio frequency currents will pass without causing heating of the condenser or terminals. 15 In testimony whereof We affix our signatures.

.ALEER NYMAN. ff" l l a IAM DILER.

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