US 1873548 A
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Description (OCR text may contain errors)
Aug. 2- s. l. mu: 1,873,548
CONDENSER Filed Jan. 29, 1930 INVENTOR.
Samuel I 00/0 Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE- SAMUEL I. COLE, 01 BROOKLYN, NEW YORK, ASSIGNOB TO AEBOVOX WIRELESS COB- POBATION, A CORPORATION 01 NEW YORK connmzsaa Application filed mm, 29, mo. Serial in. 424,219.
The device of the present invention and the method of manufacturing it may find a wide and varied range of utilit but both the article and method are pecu iarly applicable 6. to small fixed capacity condensers for use in radio receivin sets.
An object o the invention is to fabricate expeditiously by mass production methods, a simple, rugged, durable condenser of this 10, t pe, the capacity of which is accurately preetermined within narrow limits and maintained substantially invariant under all conditions of use.
Another object is to provide a condenser II which may bereadily and firmly attached to the chassis or frame of a radio receiving set and electrically connected in the receiving circuit without the need for special insulating fittings even though the chassis be of conduc- U tive material.
In a preferred embodiment of the invention, the condenser comprises a stack of conductive and dielectric sheets with stackstraddlin terminal members at opposite ends of t e stack. The stack is completely embedded in a body of molded insulating material with the terminal ends projecting beyond the body and with the body itself apertured for the reception of supporting screws or the like.
A feature which contributes materially to the expeditious fabrication of the article is the fact that the stack with its terminals may be handled as a unit. The material to be molded is in dry tablet form. It is thus merely necessary to place the stack and terminal-unit between a pair of tablets in the mold and apply the necessary heat and pressure to effect the flux and welding of the molding material. The capacity of the stacks before they are moldedis predetermined in a known manner at a rating somewhat below desired rating of the finished condenser, the pressure of the moldin press being relied wherein:
upon uniformly to raise t e capacity to the Fig. 1 is a perspective view of a condenser embodying the invention,
Fig. 2 is a longitudinal sectional view through the condenser on a considerably magnified scale, and taken approximately on the line 22 of Fig. 1,
Fig. 3 is another enlarged lon itudinal sectional view of the condenser ta lren approximately on the line 33 of Fig. 1,
Fig. 4 is an enlarged transverse sectional view on the line 4=4 of Fig. 2,
Fig. 5 is a diagrammatic sectional view illustrating the manner in which pressure is applied to the condenser stack in the early st es of its manufacture,
'ig. 6 is a vertical sectional view through one of the molds in which the condensers are formed, this view showing the various elements of the completed condensers in the mold prior to the time that the molding pressure is applied,
Fig. 7, is a view on an enlarged scale of the condenser stack and its associated terminal clips ready for a plication to the mold, and
Fig. 8 is an en arged perspective view of one of the terminal clips.
A full understanding of the construction of the condenser itself may best be had by following the various steps in the method of manufacturing it.
The condenser stack which appears in Fig. 5 consists of a plurality of alternate laminations of foil 10, and dielectric sheets 11, preferably of mica, the ends of alternate foll sheets projecting from opposite ends of the stack. The method of impregnating the stack with paraflin or the like, as well as the method of compressing the impregnated stack may,if desired, closely followthe method disclosed in the prior Patent N 0. 1,650,395 of Samuel Siegel, grantedNovember 22nd,
1-927. Briefly, the "stack is first immersed in a body of melted impregnating material,
such as paraffin which enters between the adjacent foil and dielectric laminations and forms an insulatin coating over the entire stack to prevent 'su bsequent attack by moisture. The stack is next laced between a.
air of plates 12 (Fig. 5 Pressure and eat are then applied concurrently to tioroughly compact the stack, and squeeze out excess impregnating medium from between the stack laminations. In order that uniformity of capacity may be obtained, the foil 5 and mica surfaces are originally calculated so that the condenser will have a capacity slightly above that required when the stacks enter the press and then part of the outer foil sheet is trimmed ofii' until measurement shows that the capacity has been brought handles and centering devices for the stack,
5 when the latter is emplaced in a mold as will be later described. Each terminal includes a flat plate-like portion 14, having'a tab projecting from one edge thereof and formed integral with a terminal eye 17, lying in a plane parallel to the plane of the plate to which it is connected by oflset bridge 16. Laterally of the tab 15, plate 14 is bent upwardl as at 18, and then turned backwardly, provi ing a second plate portion at 19, parallel to, but spaced fromtheplate portion 14. When these terminals are slipped over the ends of the condenser stack, portions 14, 19 straddle the stack and grip the terminal ends of the respective series of foil sheets, sufiiciently firmly so that the terminals may serve as handle members in subsequent handling of the pre-formed stack. The projecting terminal eyes 17 may be conveniently used as handles for lifting the stack about.
It will be understood that the pressure exerted on the stack by the terminal members which embrace it is less than the pressure originally applied in forming the stack so that the terminal members or clips whether of soft bendable metal or spring metal, can
. have no effect on capacity determination in the completed. condenser, nor can they vary the original capacity determination resulting from the original forming pressure.
The next step of the process is completely to embed the stack in molded insulating material, leaving only the terminal eyes 17 protruding. In Fig. 6 is shown a three part mold for the purpose, consisting of a center section 20 and upper and lower sections 21 and 22. The sections 20 and '21 of the mold are formed with complementary mold defining depressions 23, whereas, the lowermost section 22 carries aligning pins=24 accommodated in suitable bores 25 in the plates 20 and 21. These ins receive the terminal eyes 17 ofthe terminal clips 13, whereby the stack is held in proper position within the mold. In practice, two tablets 27 of powdered bakelite are placed at opposite sides of the condenser stack. The lower tablet is first positioned in the mold recess of the plate 20, the preassembled condenser stack with its terminal clips is then laid upon this tablet, the eyes of the terminal clips being slipped over the posts 24 to center t e stack. The upper tablet 27 is then laid on the top of the condenser stack and the topmostsection of the mold applied. The various sections of the mold are equipped with suitable guiding pins 28 maintaining alignment of the mold sections when the mold is placed under a press and subjected to heat and pressure.
As the various sections of the mold move together under pressure, the two tablets 27 flow and weld to each other and take a smooth hard surface finish, the bakelite material completely embedding the stack and leaving only the terminal eyes projecting. The upper mold section 23 is provided with a cut away portion 29 to accommodate the tabs 15 and thereby prevent them from being broken off under the press.
As the molding operation is carried out,
not only are the mold sections 20 and 21 moved together but the mold section 22 moves upwardly relatively to its section 20 and carries a pair of fixed pins 30 through the bakelite at a point beyond the condenser stack. These pins form a pair ofeyes 31 in the completed condenser which serve for the reception of suitable attachment devices to connect the condenser to the chassis of a radio receiving set or to mount it in any other convenient location. 4
Inasmuch as the eyes 31 are formed in the bakelite, they permit the condenser to be mounted upon metal chasses such as those now employed, without the use of supplemental insulatingmeans associated with the attaching devices.
The line 32 in Fig. 1 indicates the line of division of the two mold sections, a flash of excess bakelite being extruded from the mold under the press and when broken off leaving the slight line of demarcation apparent inv Fig. 1.
This molding operation when carried out under proper 1 ressure raises the capacity of each condenser to the desired capacity rating for the finished product, moderate care in the performance of the method assuring accurate capacity predetermination, within narrow limits. Obviously after the molding operation is over the capacity of the condenser will not be subject to change by varying weather conditions or changing conditions of use since the stack is held' against expansion of the hard molded body and is thoroughly protected against access of air or moisture. The condenser is flat, narrow and slightly elongated and both the attachment openings 31 and the terminal eyes 17 are disposed at the ends of the condenser in'a position for most convenient attachment to a support or lead wire respectively. Thus when connecting the condenser in an electrical circuit, there is no need for fumbling about with the wires or using any excess wire or excess length of bus-bars to establish a circuit through the condenser stack.
The finished condenser thus affords con venient mounting facilities and convenient electrical terminal facilities distinct therefrom, each having specialized adapation for its intended purpose. Yet the condenser is of compact dimensions the over-all width thereof in a convenient commercial embodiment being not more than inch.
It will thus be seen that there is herein described a method and article in which the several features of this invention are embodied, and which method and article in its action attains the various objects. of the invention and is well suited to meet the requirements of practical use.
As many changes could be made in the above method and article, and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 4o 1. As a new article of manufacture, a condenser of fixed capacity, including a preexposed the protruding ends of the terminal clips, said molded body havin apertures through the thickness thereof lieyond the ends of the embedded stack and laterally of said clips, said terminal clips protruding substantially from one of the lateral edges of the condenser case, and said mounting apertures being disposed substantially at the ends of the opposite lateral edges of the condenser.
4. As a new article of manufacture, a con- 75 denser of fixed capacity, including a preformed condenser stack having terminal clips only frictionally attached thereto and protruding from the opposite ends thereof, a body of molded insulating material embedding said stack and permanentlylockingfihe clips thereto and through the ends of w 'ch the terminal clips protrude, said molded body having apertures through the thickness there-. of beyond the ends of the embedded stack and laterally of said clips.
Signed at Brooklyn in the county of Kings and State of New York this 22nd day of January A. D. 1930.
- SAMUEL I. COLE.
formed condenser stack havin terminal clips pre-assembled therewith, an only frictionally engaging the stack and protruding from the opposite ends thereof, a bod of molded insulating material of but slig tly reater area than the stack embedding sai stack and locking stack and clips together and through the ends of which the terminal clips protrude, said molded body havin apertures in its ends through'the thickness t ereof just beyond the ends of the embedded stack and just laterally of said clips.
2. As a new article of manufacture, a condenser as set forth in claim 1, and wherein the clips include eyes at the exposed ends thereof offset to a plane parallel to and beyond'that of the molded casing.
3. As a new article of manufacture, a condenser of fixed capacity, includin a reformed condtnser stack having terminal 0 i s includin portions frictionallyembracingt e stack an portions rotruding from the opposite ends thereof, abody of molded insulating material embedding said stack and leaving