Патент USA US2118190код для вставки
May 24, 1938. F. w. GODSEY, JR., ET AL 2,118,190 VARIABLE CONDENSER Filed Sept. 5, 1935 2 Sheets INVENTORS ?zANK W GODSEYJ/Z. & ROBERT C. SPRAGUE ATTORNEYS May 24, 1938. F. w. GODSEY, JR, ET AL 2,118,190 VARIABLE CONDENSER 2 Sheets-Sheet 2 Filed Sept. 3, 1935 II II II II BY VEGWVT FR.Wm,KRWTGhbm.lwwmANSHT EYUO E ,6 N RE ma mv2 m 2,118,190 Patented May 24, 1938 UNITED STATES PATENT OFFICE 2,118,190 VARIABLE CONDENSER Frank W. Godsey, Jr., North Adams, and Robert C. Sprague, Williamstown, Mass, assignors to Sprague Specialties Company, North Adams, Mass, a corporation of Massachusetts Application September 3, 1935, Serial No. 39,020 (Ci. 175-415) 2 Claims. responding contraction of the plates takes place. The present invention relates to variable con densers of the type as used for trimmer or pad- . ding condensers, antenna condensers, etc. Condensers of this type have to meet various 5 manufacturing and operating requirements. For instance, they must be small and compact, in expensive, easily adjustable, and be so designed as to readily lend themselves to economical manu facture in mass'production. In addition, they 10 must be mechanically stable and return to the same capacitive setting after being subjected to a heat cycle. Furthermore, the adjustments must be simple and continuously variable throughout the rated capacity range of the condensers, and 15 any obstacle interfering with a. continuous ad justment, suchas binding of the elements or of the adjusting means, undue friction, and the like, is to be avoided.v Such condensers usually consist of at least one ?xed and at least one ?exible and adjustable metal condenser plate, between which metal plates is disposed a plate or layer of dielectric material, for example of mica. To obtain a con tinuous variation of the capacity by manual ad 25 justment, the ?exible plate is made of resilient material having a high degree of elasticity, and its capacitive relationship to the ?xed plateis varied by ?exing it toward or away from the ?xed plate by means of adjusting screws, nuts or 30 the like. . . The main di?iculty heretofore encountered with this type of condensers, was due to a sidewise dis placement of the ?exible plate relative to the fixed plate, and/or a binding of the condenser plates and dielectric plates, due to inadequacy of the mounting and adjusting means, and especial ly due to a lack or inadequacy of the guiding means. ' - Such a relative displacement of the condenser 40 plates or their binding was not only brought about in prior art condensers when the adjustment oi the condenser was changed, but also took place with a set adjustment, due to the successive ex pansions and contractions of the condenser 45 plates, as a result of the heat cycle which the condensers undergo in use; this because the con densers are used as a rule in devices, for example in radio receiving sets, in which a considerable heat development takes place during operation, 60 so that even if the heat development in the con denser per se is negligible, it heats up because of the heat developed in the radio set. Such heating up causes an expansion of the condenser plates, and when the radio set is placed out of operation and the condenser cools down, a cor To overcome some of these di?iculties construc tions have been suggested in which the end por tions of the ?exible condenser plates were riveted to the base. This expedient besides considerably increasing the size of the condenser—as much of the total area of the plates merely serves for their anchoring without adding to the effective capacity of the condenser-permits the plates to expand only in one and not in two directions, as a result of which strains are set up during the heating and cooling cycle, which cause the buck ling of the plates and may also result in other mechanical defects. To permit the plates to have relatively free ex pansion and contraction in both directions, con structions were suggested which limited the free dom of the condenser plates merely by guides placed sidewise to the plates. Such guides as a rule are expensive and necessitate the use of ex 20 cessive material. It is the object of our invention to eliminate the above referred to dililculties, and to provide a condenser, which for a given capacity value, is more compact and requires less material than 25 the prior art condensers. Another object of the invention is to provide for guiding means of thecondenser plates, which provide merely the three guiding points theoret ically required for the proper- location of one body 30 with respect to another. Another object of the invention is to combine two condensers into a. single unit with novel ad justing means permitting individual adjustment of either condenser from the same side of the unit. A further object of our invention is to eliminate objectionable capacitive coupling in a multiple condenser structure. Further objects and advantages of our inven tion will appear as the speci?cation progresses. In the drawings forming part of this speci ?cation, ‘ Figure 1 is a plan view of one embodiment of our invention; _ Fig. 2 is a cross-sectional elevation along lines 2-—2 of Figure 1; Fig. 3 is a cross-sectional elevation of a twin or dual condenser made in accordance with our in vention; Figs. 4 and 5 are plan views of a condenser plate and of an insulator plate respectively, used‘ in connection with the ‘condensers shown in Figs. l-3; 2 ariareo plate 3.5 register with the hole I‘ and the ribs 20-20 respectively. Fig. ii is a side elevation at the dual condenser of Fig. 3; _ Fig. 'i is a fractional bottom view of the corn denser of Figs. 3 and 6. Fig. 8 is a partial vertical sectional view show ing a variation in the adjusting means of the condenser of Figs. 3 and d; It will be noted from Fig. 1 that in the as-_-_ sembled condenser one of the metal plates, for example the ?at plate 25, engages with its notch Blithe corresponding left-hand rib 20, whereby its left-hand edge 98, ialls at a distance L from the left-hand wall I8 of base in; whereas the right-hand edge 99 contacts with the right side wall l8. Thus, when plate 25 is expanded by heat,‘ it can freely expand in both length and width directions, whereas at the same time it is securely guided at the three theoretically re I Fig. 9 is a plan view of another form of coin denser, in accordance with our invention; Fig. 10 is a vertical section taken on the lines M) l?-IO of Fig. 9; Fig. ii is a plan view of still another i'orm of condenser, in accordance with our invention. quired points; two such points being provided by its right side edge 99 hearing against side wall i8, and the third point being aiforded by the Fig. 12 is a vertical section on the lines Eli-l2 of Fig. ll. - . Referring to Figs. 1 and 2, a molded base it of insulating material such as arti?cial resin or the like, having rounded corners ii, is provided on its top with an open-ended shallow recess, be tween the side walls l8 of which is placed a con denser assembly A, later more fully described, and has on. its twosides upwardly-projecting in tegral mounting lugs iii-412 having holes l3--li'i to receive suitable attachment bolts. - A central hole M of the base it is adapted to 25 receive a. slotted-end screw [15, which screw pro ,iects upwardly above the‘top face i6 of the base it and passes through the condenser assembly A. The screw l5 with a nut l1 forms the ad 30 lusting means for the condenser. inwardly from the lugs l2—-l2 extend rounded guide'ribs 20—2il, which are preferably integrally molded with the base it. The ribs 20-20 serve to locate the con denser assembly A and to guide the ?exible plate 35 semicircle contact between notch 30 and the left hand rib 20. To be able to freely expand in all directions there must be a slight clearance be 20 tween the end rib 20 and notch 30. The insulating plate 35 is placed on top of plate 25 and extends substantially irom one side wall E8 to the other side wall 58, and also extends beyond both ends of plates 25 and 25'. The vaulted and adjustable plate 25’ lies with 25 its left-hand edge 98’ close to the left-hand wall l8, whereas its right-hand edge 98' is spaced from the right side walllii, and its notch 30’ engages the right-hand rib 2m in a manner similar to that 30' of plate 25. It will be also noted that the inclined exten sion lugs 21 and 21' extend at the'same end, but at opposite sides of the assembly. Onv top of the ?exible plate 25' there is pro , vided a concave spring washer 40, by which‘ a 35 uniformpressure can be exerted on the assembly A under action of nut l1. The adjustment of the condenser depends on condenser assembly A and contact with parts 1 the position of nut I1, and by exerting a greater thereof '/alon_g a semicircle of small radius. or smaller pressure on plate 25’ this plate is ?exed 4.0 The condenser assembly A consists of two me of the assembly. , It will be noted that the ribs ‘ill-e20 are dis posed on opposite ends of the shortvaxis of the to a greater or lesser amount and thereby ac tallic condenser plates 25 and 25' (see Fig. 4) of identical shape except that plate 25 is flat, whereas plate 25' is concave downward.’ The cordingly changes its capacitive relation to the ?xed plate 25. plate 25' is of highly resilient spring material, Figs. 3 and 6 illustrate a twin condenser ac cording to our invention in which two individual 45 for example phosphor bronze, whereas plate 25 may be of the same material, but may also be of non-resilient-material. adjustable condenser assemblies B and B’ are mounted on a common base 50 and are inde - The plates 25 and 25' are provided with cen tral clearance holes 26 and 26' respectively 50 which are su?lciently large to permit noncon tacting passage oi screw l5-and also with ex tending integral and inclined connection lugs ill and 21’ respectively. The plates 25 and 25' fur thermore are provided with two rounded end pendently adjustable from the same side. The upper portion of the base 50, ‘which receives as sembly B, is substantially identical with the base 50 l0 shown in Fig.2; the base 50, however, extends downwardly and is provided with an open-ended recess having side walls |8’-—I8’, ribs 2G'-23', and downwardly-extending mounting lugs i'W-A 55 notches 29 and 30, and 29' and 30' respectively. placed I2’. The within condenser the recesses assemblies formedB on and the The notches 30 and 30' are of a size to ?ttingly - surround the ribs 20—20, whereas notches 29 and 29’ are larger so as not to engage the ribs 20-20 when the plates 25 and 25' are mounted on the 60 base. ' , When assembling the condenser the plates 25 and 25’ are placed with identical faces turned toward each other, i. e., with lugs 21 and 21' on opposite sides and with notches 29 and 30' and notches 29' and|30 respectively on the same side of the assembly. .' I A thin plate 35 (see Fig. 5) of dielectric mate lie], for instancemica, and having a slightly greater length and width than metal plates 25 70 and 25', is interposed between plates 25 and 26'. The dielectric plate 35 is provided with two iden . and lower portion of the base 50, in the a manner as has been described in connection with condenser assembly A of Figs. 1 and 2. For the individual adjustment of the two con - 60' densers there are provided adjusting means whl sh comprise a metallic bushing 5| having at the lower end two preferably knurled annular ?anges molded into the middle portion 01' the base 50. , The bushing 5| extends upwardly beyond the 65 base 50 and is provided with internal and external threads. - - Against the bottom face of the condenser as sembly B’ lies a washer 56 (see Fig. 7) of insu lating material having a substantially elliptical 70 contour} a flat bearing face, and a conical face. tical notches 31-»31 adapted to snugly engage ‘ The washer 56 is provided with‘ a central counter the ribs 20'—V20, and with a central hole 36 which is smaller than holes 26 and 26'. In the assem is bled condenser, the hole 36 and slots 31—-31 of bored hole I00 and with two notches 63-43 provided at the two ends of its long axis. Into the counterbore, of hole I00 _?ts the head 51 of a 75 3 2,118,190 bolt 55, which is provided at its upper end with a slot 65 and engages the internal threads of bushing 5|. The notches 58-58 engage the lower ribs 20’—20’, and thereby fixedly hold the washer rower in width than the depressions 10 into which it ?ts. One end of the plate 80 is provided with an extension or terminal lug 8I, which passes 58 against rotation. whereas the other end of the plate 80 falls short A nut 54 engages the ex ternal threads of bushing 5| and presses against the spring washer 40. of the opposite end of depressions 10. The short oblique edges of plate 80 (see Fig. 9) The adjustment of the'upper condenser assem are so proportioned as to guide the plate in the bly B is eii'ected in a manner similar to that ex depressions "I0 by the matching oblique sides 83 10 plained in connection with Fig. 1 by turning the nut 54. Adjustment of the capacity of the lower condenser assembly B’ takes place by moving the bolt 55' along the internal threads of bushing 5I using slot 65. 15 slopingly downwards through the channel ‘I8, _ It will be thus noted that the capacities of the two condenser assemblies B and B’, can be ad justed independently, and that both adjustments thereof. A central clearance hole 84 within plate 10 80 permits the passage of an adjusting screw 85 therethrough. Plates 90, which are similar in size and shape to the plate 80, are provided with lugs 8| passing slopingly down through the right-hand channels ‘I3. The plates 90, which are of heavy and re silient material, for instance phosphorusgbronze, can be e?ected from the same side of the unit, are concave downwards and are also provided which is especially desirable when the condenser with central clearance holes 92 for the passage 20 therethrough of the adjusting screw 85. The thin octagonal-shaped pieces 86 of mica or 20 is mounted on a panel or in an inaccessible place. A variation of the adjusting means shown in Figs. 1, 3, and 6 is shown in Fig. 8, wherein a metallic insert 60 is rigidly molded in the insu lating base 50 of the condenser, and is provided 25 with an externally-threaded extension 6|. The extension 8| is provided with a smooth inner bore adapted to snugly receive a bolt 82 recessed into the washer 58 to prevent turning, and extending upwardly through same and beyond the top of 30 the extension 5| to receive an adjusting nut 63. In the constructionshown in Fig. 8 adjust ment of the lower condenser B’ is effected by turning1the nut 83 against the upper end of ex tension iI, whereby condenser B’ is to a greater or lesser extent compressed. Condenser B is ad justed by turning nut 54—adapted to ?t the ex ternal threads of extension IiI-—whereby pressure is transmitted through the concave washer 40 to the condenser assembly B. Referring to Figs. 9 and 10, a molded base I20 of a suitable vitreous insulating material and hav ing parallel faces 68 and 88 and rounded corners 88 is provided with three mounting holes 81 lo cated on one central axis'thereof. On either side 45 of the central axis are disposed identical con denser assemblies C-C later to be more fully other insulating material which separate the plates 80 and 90, have a greater width and length than do the plates 80 and 90 and extend longi tudinally to the ends of the depressions ‘IO-‘I0 25 and laterally into the openings ‘II-‘II and in dentations ‘I2—-12, whereby the plates 80 and 80 are effectually insulated from one another. The insulating pieces 86 are. each provided with a central hole 88, of smaller diameter than that of 30 the holes 84 and 92, whereas oblique sides closely fit the matching oblique sides of the depressions and are ?xed thereby. ' A circular washer 85 of bakelite or other insu lating material, and a thicker metallic washer 58 35 of similar size and shape are placed over the upper plate 88 in the order given; the’ latter washer bearing against the under side of the head of the adjusting screw 85 which extends through the holes of washers 55 and 96 and into the 40 threaded portion of the insert 14. Rotation of screw 85 changes the capacitive adjustment of the condenser by decreasingor increasing the ?exure of the upper metallic plate 80. Figures 11 and 12 illustrate a form of construc tion adapted to multiple condensers; only one unit being shown here. In the form shown in these ?gures the base H5, which is of metal, acts as a described. The face 68 is provided with two identical de pressions ‘I0—'I0 having octagonal cross sections ' fixed plate for condenser D, and is provided with 60 arranged with their longer'axes parallel to the upturned edges II5, one of which is extended to form'a mounting and terminal lug III. axis of the holes 5'I—-6‘I. The depressions con nect along their respective outer side with open The condenser unit, later to be more fully de- ' ings ‘II_‘II and' with indentations ‘I2—‘I2 along scribed, is rectangular in shape and is guided on three sides by the upturned edges H8, while the their inner sides; openings 'II—‘II and indenta tions ‘I2--'I2 extending in the same direction as fourth side is guided by two tabs I I8 pressed up the depressions ‘III--‘I0which also connect at both wards from the bases II5, which tabs also serve ends with molded channels 13-13 extending to guide one side of an adjacent unit (not shown). The upper plate I05 is rectangular in shape and through the base I20. ' " The base I20 is also provided with two similar has a narrow downwardly-bent terminal lug I05; internally-threaded metallic inserts ‘I4 (only one the base H5 and one side H6 being cut away in 60 oi.’ which is shown), having hexagonal heads ‘I5 Fig. 12'at .I III to more clearly show this. As shown in Fig. 12, the upper plate I05 is com recessed in corresponding indentations ‘I6 in the face 58 and having their upper ends crimped, as pletely compressed, but in its free condition this indicated at 11 upon cushioning washers “I8 cen ,05 trally located in recesses ‘I9 in the bottom of the 70 plate is concave downwards in the direction of its long axis. A thin rectangular-shaped separator 65 ydepressions ‘I0. The washers ‘I8 may be omitted I0‘I of mica or other insulating material (as seen ii the base I20 is made of bakelite or similar type of molded plastics, but are used when the base is of vitreous material, for example, porcelain or in place in Fig. 12), separates the base H5 and the plate I05, and overlaps all edges of the the like. An upper insulating plate III of the same size 70 and shape as the separator I01, but of greater thickness, is placed over the plate I05 and trans mits the pressure of the adjusting screw III to » The condenser assemblies C—C (only one of which is shown in section in Fig. 10) comprise a _ lower metal plate 80 and an upper metal plate 88 separated by a thin insulator 88. _ The plate 80 75 is substantially octagonal in shape and is nar plate I05. _ the flexed plate I05; plates I05, I01 and III being each provided with central clearance holes, per 75 aria, 1% 4 mltting the noncontacting passage of the screw H2 therethrough and onto cooperating threads in the lease lid. The plate ill is oi such length that it substan tially ?lls the space between the upturned edges iii, and is provided on its shorter sides with slots ll! adapted to receive upturned extensions tilt of the plate £105, which extensions terminate he low the top suriace of plate ill when assembled, iii and whereby the plate M5 is effectively guided. We have iound that in past constructions in which two condenser assemblies were mounted What we claim is: l. ‘in an adjustable condenser, a base of insu lating material provided with a lateral recess open at the ends, each side-wall of said recess be ing provided with an inwardly-projecting rib, a condenser plate provided on one side edge with a small notch and on its opposite edge with a larger notch, said plate being disposed in said recess with the larger notch clearing one of said’ ribs and with the corresponding edge in contact 10 with the side wall, the opposite edge of the on a common loose, a capacitive intercoupling occurred between the two condensers due to the plate losing spacedly located vfrom the opposite side wall with the small notch ?ttingly engaging the corresponding rib. 16 metallic parts or the adjusting means. This drawback is eliminated in our construction by making the bolt 55 (see Fig. 3) ct insulating material, or by so dimensioning the metallic parts of the adjusting means that the capacitive eilfect on one side edge with a small notch and on its y of the third condenser so formed remains below objectionable values. .As a rule it is sumclent it the capacity of this third condenser does not ex ceed 2% of the capacity oi the condensers oi assemblies B and B’. While we have described our invention on hand or specific examples and in speci?c applications, we do not wish to he limited thereto, but desire the appended claims to he construed as broadly as permisoihle in View at the prior I 2. in an adjustable condenser, a base of insu lating material provided with a recess having two opposite side walls each provided with an in wardly-projecting rib, a condenser plate provided opposite edge with a larger notch, said plate be ing disposed in said recess with the larger notch clearing one of the said ribs and with the corre sponding edge contacting the side wall, the oppo site edge oi’ the plate being spaced from the oppo site side wall with the small notch ?ttingly en- . gaging the corresponding rib. IF‘RANK W. GODSEY, Jn. RQBERT C. SPRAGUE.