US1563440A - Variable condenser - Google Patents

Description

Dec. 1 1925 LSSTSMO A. RUSSELL VARIABLE CONDENSER Filed Feb. 3., 1925 I subject of the To all whom, t may concern:

Patented Dec." 1925.

UNITED STATES l 1,563,440 PATENT oFFlcE.

ARTHUR RUSSELL, OF BALTIMORE. MARYLAND, ASSIGNOR TO THE RUSSELL RADIO ICOBPORATION, OFVBALTIMORE. LIARYLAND. A CORPORATION OIE'` MARYLAND,

VARIABLE ooNDENsER.

Application filed February 3, 1925. SeriatNo. 6,501.

Be it known that I, ARTHUR RUSSELL, a

Kino' of Great Britain. residing in ,the city of altimore,` State of Maryland. U. S. A., have invented certain new and useful Improvements inV Variable Con'- densers, Vof whichthe following is a specification. l 5

' One of the importantdiiculties incident to the operation or" radio `receiving sets. is'

that incident to tuning in on the various stationswhich in the main consists in adjusting the condenserv to the particular wave length of the sending station from which it is desired to receive.` 'The 'commonest type of variable condenser consists of a stator composed of a series 'of stationary spaced metal plates and a rotor consisting of a second series of rotatable spaced metal plates which intermesh with the plates of the rotor, Aand are spaced therefrom by a suitableair gap. The stator plates are insulated from the rotor plates' and all of the plates arel in planes at rightvangles to the axis of rotation.

In the present well-known type of variable condenser thus described, the desiredadjustment as to wave length is obtained by moving thelrotor about its axis` relatively to the stator so as to change the rela-v tion of the plates, changing the cross-section oi the air gap between the plates ofthe stator` and the plates of the rotor without changing the spacing, ordinaril)T termed the width,y of the air gap.

The dial by V,which the rotor is turned and by which its position is indicated, is ordinarily connected directly tofthe axis ot the rotor, and the adjustment requisite to satisfactory results is Vso tine as tox make it exceedingly diliicultvto obtain in this way, wherein is involved the necessity for a high degree of skill on the part of the operator.

- A further difficulty is that the variation or band ofwave lengths. obtained by the ad'- `manufacturers to make and the dealers to carry in stock condensers of various capacities having different numbers ofiplates andv further making vit necessary for the radio enthusiast who rebuilds his set, tochange and possibly discard his condenser with corresponding frequency. and expense.

'The presentinvention eliminates andovercomes to a large degree the defects and difficulties thus presented, giving a much liner adjustment to wave lengths with a less exercise of skill on the part of the operator. at the Sametime providing for adjustment or timing of the apparatus to a -much greater variation,l or as. it is stated inv the terminology of the art, to a much broader band of wavelengths than any otl the condensers now in use.

Also the apparatus permits of an easy and quick adjustment as to rits capacity, so that for the ordinary commercial apparatus it is only necessary to manufacture a condenser of a single capacity, and it is only necessary for the dealer in such commercial apparatus to carry a single condenser or` condensers of a single capacity in stock, and the radio enthusiast oramateur who rebuilds his set may change the capacity of his condenser at will to conform to the corresponding change in his set. The improved condenser .may be produced economically atdecreased expense com'pared to the present type, and it. is so constructed that it is less apt to get out of order than are the' commercial types of condenser now in use, and it maytherefore be described as offlonger life or longer v average life. l

lcoi-responding points of any circle drawn about the same axis as a centre. Preferably the plates are spirally Woundor coiled aftcr themanner of a clock spring. the width of the plates being parallel. to the axis, anfl one plate isenclosed Within the other. As

shown, the rotor is enclosed` within the stator,y i. e., has each turn, loop .or coil placed between two corresponding turns or coils ot the stator, so that the two plates or bands are substantially concentric and parallel and rotatable through anarc, one relativelyto the other.

. the lparallel relation .and gives a change of spacing of the plates and a wide change of capacity of the condenser. In the form shown the stator plate `orspiral is secured to the panel and the rotor is mounted on a. shaft for angular adjustment relatively to the stator about the axis ofthe stator and its own axis whiclrare preferably identical.

For the purposes of this adjustment as to capacity, I have provided a dial or similar' member connected to the vrotor by which it may be rotated and its position relatively to the panel and the stator suitably indicated;

For the purposes of adjustment of the apparatus to the Wave lengths of the various the capacity adjustment.

stations from which it is desired to receive, one of the plates is moved relatively to the other in a direction parallel to the axis in any suitable manner. Preferably the rotor ismounted to move along the shaft into and out of the stator, changing the cross-section of the air gap. Inthe form shown the adjustment as to wave lengths is obtained by means of a screw threaded, akially placed rod or pin extending through the shaft on which the rotor is mounted, by which threaded pin the rotor is moved in the direction of its axis relatively to the stator `by turning a suitable nut or knob engaging the thread, giving an exceedingly vwide range of adjustment, making it possible to change the cross-section ofthe air gap from zero -to the maximum available when the rotor is almost or completely enclosed Within the stator. The rotor is during this operation held against rotation by means of a suitable key or equivalent device which connects it to the shaftwith which it is turned during The axial adjustment provides for variation of the cross-sectional area, of the air gap land by means of the screw and knob,a much finer adjustment as to this element,

which tunes the set to theI wavelength of' thesending set, may be obtained than with the type of condenser in which the rotor plates are merely swung by means of and with the dial, and at the same time this apparatus obtains or provides for an adjustment to a greater variation of wave length 1 or broader band of wave lengths than can be obtained by any 'other known instru- ,1t-@11t- 110" Provided fer this puriose.

In the accompanying drawings I have illustrated 'a variable condenser embodying the features of my invention in the pre,- JEerred form. y i

In the drawings- Figure l is a longitudinal section on the plane of the axis of the condenser plates showing the complete condenser assembled.

Maaate rotation to provide for variation of capacity. The adjustment is for maximum capacity. f

Figure l is an elevation looking at the front of the panel showing the dial, knob, etc., at minimum capacity. t

Figure .3 is a section on the line 5,5 of Figure l through the hollow shaft, screwadjusting pin and hub, showing the stop'` which limits the rotation of the hollow shaft and therefore the angle through which the plates may be rotated to adjust for capacity. 3

Referring to the drawings numerals, each of which is used to indicate the same or similar parts in the different figures, the variable condenser as shown comprises concentric and substantially'parallel ,condenser platesyone enclosed Within the otherand indicated by reference characters l and '2, the plates beingshown'each in the form of a coiled or spiral band having theiriwidth parallel to the axis of the spiral and each having its respective tiirns equally spaced and Msubstantially parallel, the pitch being uniform throughout, and as is-usual-in such apparatus, the stator l is insulated from the rotor 2.

or more properly to the condenser base 4 by means of suitable clips on brackets 5 which may be soldered to the stator plate and bvy screws 6 engaging the brackets 2.v

The base t is' in turn securedto the anel. Both the base 4 and the panel 3 are o hard rubber or other suitable insulating material. The' stat-or pla-te l is preferably spaced .away from the base, as indicated at 7. The plates manner as' at 6 and 6.

The loopsj or turns of the'stator plate l are spaced apart and secured inthe desired relation, and the en'tire stator coil structure. M is made rigid by radially placed studs or y K Il The stator'l'jl is sejcured to the panel 3,

110,l mayT` be connected to the circuit in the usual plate between the respective loops or turnsy of the stator plate, andthe loops or turns of the stator plate 2 are similarly bra-ced by radial studs 15 connecting them at their outer edges. i. e., the edges remote from the panel, see Fig. l, so that these studs or strutsL 13 interfere as little as possible with the entrance of the rotor plate V2.to the full width of the plate between the turns or coils` 16 secured at its radial ends within the insecured a pin 19. The

ner turn or loop 17 of the rotor. This support 16 carries a central hub 18Vto which is pin 19 is concentric and aligned with the axis of both plates, being as aforesaid secured at one end to thecentre of the rotor plate 2 and extending forwardly through shaft 22 which is made hollow to receive it, through the stator plate 1, through the panel and projecting beyond the panel for a suiiicient length to` provide' for adjustment ofthe plate 2 in the direction of its aXi/s for a large proportion of'the Width of the plates. The forward end of the pin in front of the plates is threaded at 2O to co-operate with a nut or knob 21,

suitably apertured and threaded to co-operate with the thread on the pin. The pin 19 is mounted to slide in the hollow shaft 22` which is concentric and aligned therewith andmounted in a bearing formed in a boss 24 which as shown -is formed integral with a plate 25 secured in any suitable manner to Ithe condenser base or base plate 4 or to the panel 3.

The shaft 22 referred to hereinafter as the rotor shaft may be actuated and controlled, and its position determined by a dial l 26 suitably apertured at its centre to admit the shaft and secured thereto in any suitable manner as by means of a set-screw 2 7. This dial may be suitablyV graduated at 28, see Fig. 4, and the panel may be provided with a pointer 29 to co-operate with the graduations. The resistance or friction of the panel is adjusted by means of a screw 40 seated in the dial and bearing on the panel.

The rotor shaft 22 may be connected to the rotor 2 in any suitable manner to cause the rotor to turn withthe shaft 22 and to permit the rotor to slide freely in the direction of the axis of the shaft. In the form of the invention shown this keying arrangement consists of a pin 30 parallel to the `shaft 22 and 'the pin 19 and spaced well' position the rotor shaft 22 by contact of the fiange with the end of the boss 24the hollow rotor shaft 22 being thrust forwardly, maintaining the ange.33 in contact with the end of the boss by means of a coilspring 34 Which is coiled about the rod 19 at the A rear, bearing at one end against the forward side of the spider plate 16 and at the other Aend against the flange This spring also tends to thrust the rotor plate rearwardly, i. e., to the right in-Figure 1, causing it to more to the right out of the stator as the vrod 19 is released by unscrewing the knob or Y nut 21 and permitting it to be drawn tothe left, causing it to enter the stator as vtlie vnut or knob `is turnedwup on the rod 19,

giving the desired adjustment' of' the cross Y section of the air ygap to provide for interpreting different wave lengthsx The rotation or angular displacement of t-he rotor 2 from minimum capacity position relatively to the stator 1, is'definitely limited "by means of a radially projecting stop 36, see Fig. 5, on the rotor shaft 22which rides in an open slot 37 attheend Opf-boss 21.

The minimum capacity position of the rotor, Fig. 2, is determined by the contact of the stop 36 with the edge 39 of the slot 37, and the maximum position, Fig. 3, by contact with the opposite edge 38. The spacing of the plates is thus changed and the parallel relation maintained Aby and on account of the-concentric location of the plates and the uniform pitch- These elements may be varied to some degree without complete loss of the function. Y I

In the'operation of the condenser, to adjust for. capacity to adapt the condenser to any particular receiving set, the rotor4 2 is turned 'from the position shown in Fig. 2

tothe left relatively to the stator l'toward the position inl Fig. 3 toreduce the spacing of the plates," causing the loops or turns of the rotor by the variation inradius ofthe stator and rotor, to approach the loops of t-he stator, thus changing the width of the which one or more plates of one element are j adjusted toward and' from the adjacent plates of the-other element, Vthe rotation of the lpresent type of condenser whereby the spacing of the entire rotor relatively to the stator Vis changed by a single adjustment by rotating one element relatively to the other about the common centre, is regarded as an important feature ofthe invention, producing a wide scope of adjustment as to 'capacity without lcomplication of structure and by a very4 simple operation. e

To tune the receiving set to the wave lengths of any transmitting set from which 1t is desired to. receive, the cross-sectionl lain of the air gap is changed. n exceedingly fine adjustment is obtained by rotating the nut or knob 21 either taking up or letting out the threaded pin 19. moving the rotor relatively to the stator in the direction of the common axis, changing the position of the rotor 2 as to the extent to which it is enclosed Withinv the stator 1.', and while a very minute adjustment may be easily obtained in this vvayfthereis on account of the wide possible variation ot' position of t-he rotor 2 relatively to the stator 1, a wide range of adjustment, and the apparatus may be adjusted with extreme accuracjv and Without the exercise of slrill requisite with the condenser-s now` in use, to and through a broad band of `wave lengths, than can be Letters Patent is 1. A variable condenser having a rotor and a stator each comprising a plate Wound in a Spiral about the mutual common axis7 the two plates being adapted to intermesh with and being spaced troni each other, and means to change the relative spacing between the plates by relative rotation of said rotor and said stator about the common axis..

2. A variable condenser having a rotor and a stator each comprising a pla-te Wound in a spiral about the mutual common axis, the two plates ada ted to intermesh with and being spaced rom each other, means to adjust one of said plates relative to the other in the direction of the common axis, and means to move one et the said Y plates angularly yabout the common axis of the turns of one plate with regard to the' adjacent turns of the other pla-te, and means to hold said plates against variation of said spacing.

4. In a variable condenser. a stator plate in the form of a rigid spiral, a rotor plate infthe form of a rigid spiral, said plates l having the saine uniform spacing along .a radius and adapted to interinesh with each other, the outer ends of one of said plates having a greater spacing from the adjacentturn of the other plate than the said uniform spacing, and means to vary the length of the outer end portion of said first plate having said greater spacing.

ln a variable condenser. a vstator comprising a met-al plate in the torni of a spiral having a uniform angle of intersection with aradius, a rotor plate similarly formed and adapted to intermesh with the stator, so that the turns of the respective platesare uniformly spaced along a radius, a hollow shalt for the rotor with keying means permitting the rotor to slide in the direction of its axis and securing it to the shaft to rotate therewith, a threaded .pin extending through the hollow shaft and secured to the rotor, a .nut engaging the pin to move the rotor in the direction of its axis into and out of intermeshed relation with the stator plate to adjust the eective capacity, and means to turn the rotor shaft to adjust the width of the air gap between the plates to vary the effective capacity.

Signed by me at Baltimore, Maryland, this 2nd day of February, 1925.

' ARTHUR RUSSELL.

Images