US1601281A - Variable condenser for tuning electric oscillating circuits - Google Patents

Description

Sept. 1' 28 1926. 4 1,601,281

K. J. G. AHLSTRAND VARIABLE CONDENSER FOR TUNING ELECTRIC OSCILLATING CIRCUITS Filed May 4:, 1926 Patented Sept. 28, 1926.

UNITED STATES PATENT OFFICE.

KARL JOHAN GERHARD AHLSTRAND, 0F STOCKHOLM, SWEDEN.

VARIABLE CONDENSER FOR TUNING ELECTRIC OSCILLATING CIRCUITS.

Application filed May 4, 1926, Serial No. 106,675, and in Sweden November 13, 1925.

The present invention relates to improvements in variable condensers for tuning electric oscillating circuits in which the rotatable spindle supporting the movable plates and a fine tuning spindle are connected to each other by means of a gearing device consisting of a wheel journalled on an eccentric which is supported by the fine tuning spindle and is in frictional engagement with a casing surrounding said wheel and being secured to the spindle supporting the movable plates. Variable condensers having such a gearing device are described in my co-pending application Serial No. 54,022, filed September 2nd, 1925.

The object of my present invention is to make the said gearing device variable and at the same time to simplify the device used for guiding the wheel jonrnalled on the eccentric.

The invention consists, chiefly, in this that the eccentric is movable in radial direction whereby it is possible to change the relation between the circumference of the wheel and the circular path of engagement of the casing surrounding said wheel and thus the ratio of gear between the two spindles.

In the accompanying drawing I have shown one embodiment of my invention.

Fig. 1 shows an end view of a condenser. the gearing device being shown in section on line a-b of Fig. 2, and

Fig. 2 shows a horizontal section on line (Z of Fig. 1.

Referring to the drawing, 1 indicates the frame to which the fixed plates 1 of the condenser are secured. 2 indicates a rotatable spindle supporting the movable plates 9 of the condenser. To the rear end of said spindle is secured the one part 8 of a casing 3, i, the circumferential portion of which is of wedge-shaped cross-section, as is clearly shown in Fig. 2. The two parts 3, 4 of which the casing is composed may be connected to each other, for instance, by threaded flanges 3" and 45 respectively, so that the distance between the walls of the casing may be varied.

The spindle 2 is hollow and in the same is rotatably journalled a fine tuning spindle 5 supporting an eccentric which in the construction form shown consists of a wire 6 of steel or other yielding material protruding a distance from the axle 5. The said wire 6 is disposed in a longitudinal groove 16in the spindle 5 and is at its inner end rigidly secured to the spindle, for instance, by soldering. The wire is so arranged that its free end tends to move radially outwards from the groove 16. The wheel 7 is disposed on the end of the wire 6 extend ing into the casing 3, 41-. Said "heel con sists of a solid disc of metal or other suitable material and to the same an arm 8 is secured which extends through a slot 17 in the bottom 3 of the casing and is provided at its free end with a notch 12 engaged by a pin 13 secured to the frame 1. The spindle 2 supports a hand wheel 1st and the spindle 5 a knob 15.

The device works as follows. The wheel 7 is pressed by the wire 6 into engagement with the walls of the casing 8, 4;, two opposite points of the edges of the wheel 7 engaging the conical portions of the walls of the said casing. By suitable choice of the pressure exerted by the wire 6 a suitable friction between the wheel and the casing is obtained. When the spindle 5 is rotated, the edges of the wheel will engage succes sively different points of the walls of the casing, i. e. the circumference of the wheel will roll off itself along a circular path in the casing, the diameter of which is determined by the thickness of the wheel 7 and the distance between the conical walls of the casing 3, 4;. This path is indicated in Fig. 1 by the dotted line 18. As the wheel 7 is in connection with the fixed frame 1 through the arm 8 it will impart to the casing and the spindle 2 connectedthereto a rotary motion the size of which is determined by the difference between the circular path 18 and the circumference of the wheel 7. In the present case it is, however, possible to change the size of the path 18. This can be done by screwing the cover t more or less towards the bottom 8, whereby the distance between the conical side walls will be changed. This in its turn is possible by the eccentric 6 being disposed yieldingly so that the eccentricity accommodates itself to the path of engagement for which the casing has been regulated. In this way every desired ratio of gear between nil and the maximum ratio of gear determined by the dimensions of the device may be ob tained.

In the construction form shown the wheel the eccentric make a small oscillatory rotating movement around its centre. The

- size of this movement depends on the length of the a m 8 and as a result of said move ment the ratio of gear between the spindles 2 and 5 is change'l continuilly during each revolution of the spindle Tr hen the wheel U 7 is in the position shown in the drawing, i. e. when the point of engagement between the wheel and the casing is neares to the pin 13, the ratio of gear is smallest. From this point it increases continually du *ing half a revolution until said. point of engagenent has movel to the opposite end posi and thus is at the greatest distance said pin During the following halt r v- OlllLlQll the ratio of near decreases ccntir ill ally until it at last when the revo ution is completed and the wheel 7 has'returnce into its initial position has been reduced its orginal value. Said variations of the ratio of gear which may be reduced by increasing the length of the arm 8 are in many cases of no practi -al importance, but obviously it is desirable to be able to obviate the same, it this can be done in a simple manner. ln the present case this is possible without complicating the device in any way and without introducing any new eles simply by placing; the hole or the T rig-aged by the eccentric 6 not in the centre of the wheel but slightly nearer to the guiding pin 13 or that point of enc i. iii

whee

O ga ement ot' the wheel that gives the slow-- est ratio of gear. Hereby a wheel 7 is obtained the radius of which counting to the noint of engagement increases continually JO 1 g halt revolution of the spindle 5 )OSlilOll shown in the drawing and 'ontinually in the same proportion "iol owinghalt revolution of said Thus the same result is reached were used in each new point "'gement a wheel having HlOtllGl cirth n that used in the foregoing M nient. As the path 18 reiins the some. variation of tie at o ol Q is obtained which is contrac to the i'arzation of the ratio of near caused b the arm 8 P-y suitable choice of the n "tirot the hole ot' the whee T said in can be made the same i1 size and thui Add pensate each other so that a quit ratio of gear between the two SPldf-S and s obtained.

)oviously the device described above may be varied as to their details without deviating from the principle of the inven tion.

- denser for tuning elects the combination of es, a system of movable 3 ting the said mova ii 1e tun'ng spmdle having; the of rotation as the first mentioned mg on the latter, an eccentric the said fine tuning spindle ovahle radially, a wheel jourl eccentric within the said :ase ng in frictional engagement and means for preventing the one i members being in frictional enfrcm being rotated, substantially 1' the purpose set forth. In a variable condenser for tuning; elecoscillating circuits the combination of 1 tixed plates, a system of movplates, at spindle supporting the said hie rtesa hue tuning, spindle havaxis of rotation as the first- Tndlc, a casing on the latter, a I ing material hating its one -urczl to the said line tuning 1 1, er tree end of said wire tendve outwards from the axis of roi said fine tuning spindle, a wheel led on the free end of the said wire the said casing and being in fricp grn:rent therewith, and means for ing the one of said two members herietional engagement it]: n being ro ubstant ally as and for the purpose a variable condenser for tuning elecilating circuits the combination or a )1? lined plates, a system of movz hie i, a hil oi' spindle supporting the said plates, a The tuning spindle rotat aoly journalled in the said hollow spindle, rigidly secured to the latter in tion thereto, a wire of yielding ving its one end rigidly secured fine tuning spindle, the other free vire tending to move outwards ojt rotation of said fine tr": \lle. a wheel termed with an eccent A is .7 1 m nr located, n ne loosely engage tnc ce end or" said wire, 1' re and wheel being within said casing in frictional cnth, an arm rigidly secured wheel and means for guiding" said as to prevent the. said wheel from l otated, snbstantiall as and for the pi'r 'zosc set fofirh.

1 testimoir whereof I have JQFGUHtO subsci ioed my name.

KARL JOHAN GERHARD AHLSTRAND.

Images