US2662145A - Characteristic changer - Google Patents

Description

Dec: 8, 1953 J. J. WILENTCHIK CHARACTERISTIC CHANGER Filed Jan. 20, 1950 mdE NOE Q a.

INVENTOR. %JERZYJ. WILENTCHIH v Alff aw Patented Dec. 8, 1953 UNITED STATES PATENT OFFICE 2,662,145 CHARAOTERISTIC CHAN GER Jerzy J. Wilentchik, New York, N. Y. Application January 20, 1950, Serial No. 139,572

12 Claims.

This invention relates to improvements in voltage generating systems, wherein it is desired to produce an output voltage v as a desired function o=f(x) of angular displacement as of a control means.

between successive taps.

In general, any functional voltage-rotation relationship v=-f('r) can be simulated accurately by a sufficiently large number of potential points on the curve of the function and by linear interpolating means between respective potential points.

- The instrument consists basically of a voltage divider resistance connected across a source of voltage and operating in conjunction with an interpolating potentiometer.

Intermittent connections in parallel are made between preselected sectors of the divider and the potentiometer through use of a commutator and of an intermittent-stepping coupling The sectors are selected by means of taps readily attached to the voltage divider resistance to conformto a desired voltage taper.

Several features of novelty characterize this invention overthe existin art.

One of them provides taps adjustable manually along the length of a voltage divider.

Another feature of novelty embodies the principle of combining the individual characteristicsof a voltage divider, a commutator and a linear potentiometer into a functionally adjustable voltage" generator.

For a better understanding of the invention and the specific objectives attained with its use, reference should be had to the following description and accompanying drawings in which preferred embodiments of the invention have beenillustrated' and described.

In the drawings:

Fig. 1- is a cross-section according to the invention.

Fig. 1a is. a schematic representation of the interpolating components.

to respective bars 2 of commutator i.

A voltage divider 50 consisting of turns of resistance wire a is wound along the length of helical shaped groove 3 in a non-conducting and heat resisting mandrel 5. The extremities of wire 4 are connected by a 5 pair of conductors (not shown) to a voltage source (not shown). The voltage distribution along the length of the resistance wire 4 is uniform assuming uniform threading, uniform wire material and uniform wire distribution in the grooves 3. Thus, the potential at any selected point of wire 4 is a linear function of length and can be identified easily by the number of complete and incomplete turns of said wire contained between a terminal thereof and the selected point. A cylindrical and non-conducting cup 6 encloses the mandrel 5 and is characterized by multiple turns of a spiral continuous slot 1, the latter being narrower than the width of the groove 3 and in alignment with it. A contact pin 9 is retained 510 within a barrel [0 slidingly. The upper part Illa of the barrel It is a hollow cylinder, the external diameter thereof being slightly less than the width of the slot 1'. The lower part ltb of the barrel I'll forms a flange of rectangular cross section with rounded corners, the shorter side of said flange being less than the width of slot 1, the longer side thereof being more than the Width of slot 1 and less than the width of groove 3. Thus the flange Nib is adapted to be manually inserted through slot 1 into the groove 3 when its longer side aligns with the length of slot 1 and may be locked therein by a 90 degree turn thereof to either side. A positive electrical contact between the pin 9 and the wire 4 is sustained by the inter 5-mediary of spring 8, the latter inserted in the hollow section ofthe holder I0, and adapted tobecome compressed between the pin 9 and a conducting plug l I pressed into the upper section of the cylinder I01), when the holder ID is inserted 1 the 1 1; 1, The cup 6 and the mandrel 5 are held together by screws. The plug H is connected by conductor Ha to a respective commutator bar 2. A design modification of the attachable contact is shown in Figs. 2, 3 and 4 where a contact pin 12 is provided at its middle section with a flange consisting of a pair of wings [2a and l2a of rectangular cross-section with rounded corners and tapered outside surfaces. The bottom end so of the pin I2 is, adapted to become conductively associated with the resistance. wire 4 when insorted in the slot. 7,, and may be locked therein by a 90 degree turn to one side, upon which the tapered surfaces of the Wings- IZa and. Ila coopcrate with the inner surface of the cup 6. The

wedge effect thus produced creates the necessary pressure between the point 2% and the wire 4. It should be borne in mind that the wing its is tapered convert u to the i254 the insertion in the slot By having "n complete turns of wire 4 around mandrel 5, "n being preferably a decimal number, each complete turn assumed to allow m different relative positions of the holder Ill with respect to the former, we obtain the total number of such possible positions at (mmm) which number represents the accuracy with which the instrument can be set. If 1 =l and m=100 and the input voltage is 100 volts, the resolution or the voltage drop per unit length of the resistance wire would be 0.1 volt, and the highest accuracy of output which could be obtained regardless of other factors would be 0.05%. By inserting the holder [0 in a selected suitable slot 1, and at a suitable radial location along the perimeter thereof, the potential of a respective bar in the commutator I can be controlled within 0.01 volt accuracy.

A resistance coil wound helically on a core can be of course used instead of the resistance wire 4. A pair of supports 21 and 2 la provide for an adequate elevation of the cup 6 above the ground and enable the insertion of taps It in the underneath section of slots 1 in said cup.

The following part of the specification describes the operation of the interpolating mechanism.

Referring to Figs. 1 and la, a sleeve l5 carries the commutator l and forms an internal and concentric section of the cup 6. The commutator 1 consists generally of conducting bars 2 inserted circumferentially in the plastic disc 20, arranged at an equal distance from the center of said disc and at equal distance from each other. It is understood of course, that many other designs of commutator could be used instead of the one proposed in Fig. l. A pair of similar spring contacts I6 and I! (only the contact It being shown in Fig. l) are spaced from each other at a distance equal to the center distance of a pair of contiguous bars 2, and are connected by respective conductors l8 and [9 to a pair of terminals 52a and 52b seen in Fig. la on an interpolating resistance 36. Since the maximum possible displacement of the contacts [6 and I1 is assumed less than one complete revolution the twisting of the conductors l3 and I9, extended through hollow internal section of the sleeve l5 would be negligible in this arrangement. The sleeve may be provided with conveniently located apertures to facilitate the wiring of the conductors I3 and [9. The elements [6 and [1 are attached to a non-conducting contact carrier 25 and are adapted to be displaced by a step intermittent motion in conductive engagement with said bars and along the length of the outside perimeter thereof.

The intermittent motion coupling consists of a pair of coaxial crown gears 22 and 23, the first one of said pair adapted to become rotationally entrained in the displacement of the second one, both mounted loosely on the sleeve I5. The gear 22 is provided with a number of teeth equal to the number of bars 2. The gear 23 may have a number of teeth similar to that of the gear 22, or a lesser number of teeth, provided that said teeth are distributed along the circumference of said gear at such uniform distance from each other as to mesh with respective teeth of the gear 22. A disc having a cam like projection 25a, the latter adapted to cooperate with a guide 24 soldered or otherwise attached to the sleeve I5 is mounted on the gear 23. The gear 23 is adapted to be axially displaced along the length of sleeve [5 in a direction towards the gear 22 whenever the projection 25a becomes physically engaged with the guide 24. The gears 22 and 23 become locked which results in rotational entrainment of the normally stationary gear 22 during all such times that the gear 23 and the guide 24 are in physical engagement. The shape of the projection 25a and the width of the guide 24 are coordinated to produce upon every complete revolution of the gear 23, or more specifically each time that the gear 23 and the guide 24 become engaged and disengaged, a step motion of the gear 22 and a resulting displacement of respective contacts l6 and IT by a distance which is equal to the distance between a pair of contiguous bars in the commutator I. The contact carrier 26 is mounted on the gear 22 and adapted to displace thus the contacts 16 and IT with regard to respective bars 2. The gear 23 is adapted to be entrained in the rotational displacement of the input member 3|, mounted on shaft l5 through transmitting rods 21 attached to disc 3la, the latter being a part of the member 3|. The rods 21 extend slidingly through closely fitting slots in the gear 23 and are provided with respective springs 29 adapted to return the gear 23 all the way to the right and disengage the gear 22 when the gear 23 becomes separated from the guide 24.

To obtain an accurate centering of the contacts I6 and H with regard to their respective bars 2, a locking device 30 can be used. The section. of circumference of the sleeve Ill, which carries the gear 22 is notched, indented or otherwise artifically roughened to provide for such intermittent frictional resistance that will pro duce uniform step displacement of said contacts upon each clutching action of the gears 22 and 23 and then lock them in their newly assumed position. The notches 28 are equally spaced along the perimeter of the sleeve l5, relatively to bars 2 and are adapted to cooperate engagingly with looking pointer 32, the latter being carried by the gear 22 and pressed against said notches by spring 33, the magnitude of pressure applied being controlled by adjustable screw 34. Thus the gear 22 is being protected from accidental loose motions; it may assume only few relative positions with respect to the commutator I and may become displaced from such once assumed position, only by engagement with the gear 23 which would provide an adequate amount of energy to compress the spring 33 and thus unlock the gear 22. The radial distribution of respective notches 28, their depth and the pressure exerted against them by the pointer 32 may be correlated to produce a step motion of. the gear 22 and displace the contacts l6 and H from the center of their associated bars to the center of the next following ones. The width of either one of the contacts [6 and I1 is less respectively than the width of respective bars 2, and is less than the width of the insulation layer between the latter, thus the possibility of a short circuit between any pair of such bars is eliminated.

The disc carries a plastic plate 350., the latter provided with a contact spring 35 being in simultaneous conductive egagement with interpolating resistance 35, the turns of the lat ter arranged toroidally around and along the periphery of a ring form mandrel 36a and with a conducting ring 31. Both the resistance 3'5 and the ring: 31- are insertedi. concentrically," to each other and to the: sleeve 1 5: in. respective grooves of a non-conducting holder: 38: connect.- ed to said sleeve: and'beihg'therefore stationary. A pair of pointers 40 and M may be attached respectively to the: linl-s 26- andto the disc 31a for indicating the complete and the fractional revolutions of the member 3| on dial divisions which may be marked on the cup 6. The ring 31 is connected by means of conductor 43. to the output terminal 44 of the instrument. A. stop (not shown may be attached. to. the sleeve L5 or to any other stationary component oiithe device and may be adapted. to cooperate with a cam. (not shown) in the gear 22 to limit-the. displacement of said gear to. less than one. complete revolution;

The operation of the interpolating mechanism described above is as follows:

The potentials of a pair of respective contiguous bars 2 are applied to the terminals of the interpolating resistance 35, which should in general be provided with sufficiently large ohmage not to allow an appreciable current flow through it, which could disturb the potential distribution along the selective resistance 4. Assuming that the interpolating resistance has been linearly wound, the potential drop along its length is linear and the output potential would be a linear function of displacement of the input member, such linearity holding for every complete revolution of the input member, said completer revolutions being counted in either di rection starting from the zero position of the input member. tact 35 is situated between the terminals of the interpolating resistance 35. The stepping motion device is adjusted to produce step displacement of the gear 22 whenever the contact crosses the neutral spacing between the terminals of the interpolating resistance. Thus, for complete first, second, third and any following revolutions of t e input member, linear interpolations are obtained between the potentials of respective first and second, second and third,

schematically the commutator I, its associated contacts l6 and I7, the interpolating resistance 36 and its associated contact 35, the latter connected to the output terminal 44. The contacts 16, H and 35 move in the same direction which may be clockwise or anti-clockwise depending on the sense of displacement of the input member (not shown in Fig. 1a but similar to that seen in Fig. 1). The contact 16 is connected conductively by conductor Sic to terminal 52a of the resistance 36, similarly the contact I! is connected by conductor 5th to the other terminal thereof 52?). Respective layers of insulation 53 separate contiguous bars 2. The width of the layer 53 is equal to or larger than the width of either one of the contacts 16 and 1?, thus e1iminating the possibility of a short circuit between any two bars 2. Assuming a clockwise sense of rotation of the input member, the contact 35 would be displaced clockwise from its position along the resistance 36 towards the terminal 52b. The distance separating the contacts is and i! may be made approximately equal to the width of the insulation layer 53. In the normal position shown, the contacts 16 and IT would be stationary and would cooperate with a pair of In the zero position the con- 5. contiguous; bar's 2c and 21).. When the rotating contact: 351- en'gagcs. the. terminal 5271;. the gears 22 and 23 of the intermittent motion coupling shown: in Fig. 1;. become locked: and-1a clockwise entrainment: of: both. element'sv lit and; I7 results. the: conducting area. between: the: contact l6 and the bar: 2a. diminishes. and. finallythe terminal 5521) becomes. neutralized. which corresponds to thecontact lc-eclipsing' totally the insulation layer 53a. The contact: M5 is being. displaced concurrently in conductiveengagement with the bar 2b towards the insulation 53b and its potential remains thus constant. The factzot the terminal 52w losing. its: potential does. not have an eifect on. the. potential; of. the contact 35;, since: the: latter assumes the potential of the bar 22) directly from the engaged terminal; 5:212. Upon further clockwise displacementof the input member, the contact It: would becomev conductively united with the bar 2b, the contact. I11? would engage on the insulation 53?) and the contact 35 would become conductively united with the terminal 52a and maintain thus the output terminal 44 at the potential of the bar 2b. When the contact [1 becomes in turn conductively united with the bar 20, the terminal 52b assumes the potential of the latter and a linear voltage drop between the potentials of respective bars 222 and 2c is produced along the length of resistance 36. The width of the respective bars 2 depends on the efiective conductive area of the contacts [6 and [1; it should be less than the combined length of a pair of such contacts and the insulation layer 53 and more than the length of either one of them separately. It is to be understood that the locking device 30 could be still used with this arrangement, not to produce a step motion of the gear 22 but to lock it in its normal position shown, against accidental motions.

What I claim as novel, and desire to secure by Letters Patent, is:

1. In combination, a mandrel, a groove in said mandrel, a resistance means disposed within said groove, a plurality of contact elements, locking means common to said elements and to said groove to lock said elements at any desired point of said groove in electrical engagement with said resistance means.

2. The combination according to claim 1, wherein said groove is a multi-turn, undercut cavity.

3. The combination according to claim 2, wherein said contact elements are spring loaded.

4. The combination according to claim 3, wherein said contact elements are flanged.

5. The combination according to claim 2, wherein said elements are provided with a tapered flange.

6. In combination, a mandrel, a groove in said mandrel, voltage division means in said groove, a plurality of contact elements, means common to said contact elements and to said mandrel to lock said elements at any point of said groove in conductive engagement with said voltage division means and interpolating means connected to said contact elements.

7. In combination, a mandrel, a groove in said mandrel, a recess in said groove, first voltage division means in said groove, a plurality of contact elements, means to lock said contact elements by means of said undercut at any point of said groove in conductive engagement with said first division means, second voltage division means, wiping means adapted to be conductively disposed along the length of said second division means and conductor means connecting selective points on said second division means to said contact elements.

8. The combination according to claim '7, wherein said second division means is circular in form and wherein the rotation of said wiping means is mechanically continuous.

9. The combination according to claim 8, wherein said conductor means include a plurality of studs connected to said contact elements and a plurality of sliders connected to said selective points on said second divider and to said studs.

10. The combination according to claim 9, including displacing means to move said sliders between respective studs relative to displacement of said wiping means.

11. The combination according to claim 10 wherein said studs are arranged in a single, circular array.

12. The combination according to claim 11 wherein the operation of said displacing means is intermittent.

JERZY J. WILENTCHIK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,268,712 Harle June 4, 1918 1,976,226 Hine Oct. 9, 1934 2,025,218 Reinken Dec. 24, 1985 2,446,563 Upton 1- Aug. 10, 1948 2,452,311 Markusen Oct. 26, 1948 2,471,843 Stamper May 31, 1949 2,480,102 Weisglass Aug. 30, 1949 2,494,922 Yardeny Jan. 17, 1950 2,515,606 Linder July 18, 1950

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